Key points are not available for this paper at this time.
Prolyl 4-hydroxylase (proline hydroxylase, EC1.14.11.2) catalyzes the formation of 4-hydroxyproline in collagens. The vertebrate enzyme is an α2β2tetramer, the β subunit of which is identical to protein disulfide-isomerase (PDI, EC 5.3.4.1). We report here on cloning of the recently discovered α(II) subunit from human sources. The mRNA for the α(II) subunit was found to be expressed in a variety of human tissues, and the presence of the corresponding polypeptide and the (α(II))2β2 tetramer was demonstrated in cultured human WI-38 and HT-1080 cells. The type II tetramer was found to represent about 30% of the total prolyl 4-hydroxylase in these cells and about 5–15% in various chick embryo tissues. The results of coexpression in insect cells argued strongly against the formation of a mixed α(I)α(II)β2 tetramer. PDI/β polypeptide containing a histidine tag in its N terminus was found to form prolyl 4-hydroxylase tetramers as readily as the wild-type PDI/β polypeptide, and histidine-tagged forms of prolyl 4-hydroxylase appear to offer an excellent source for a simple large scale purification of the recombinant enzyme. The properties of the purified human type II enzyme were very similar to those of the type I enzyme, but theK i of the former for poly(l-proline) was about 200–1000 times that of the latter. In agreement with this, a minor difference, about 3–6-fold, was found between the two enzymes in the K m values for three peptide substrates. The existence of two forms of prolyl 4-hydroxylase in human cells raises the possibility that mutations in one enzyme form may not be lethal despite the central role of this enzyme in the synthesis of all collagens. Prolyl 4-hydroxylase (proline hydroxylase, EC1.14.11.2) catalyzes the formation of 4-hydroxyproline in collagens. The vertebrate enzyme is an α2β2tetramer, the β subunit of which is identical to protein disulfide-isomerase (PDI, EC 5.3.4.1). We report here on cloning of the recently discovered α(II) subunit from human sources. The mRNA for the α(II) subunit was found to be expressed in a variety of human tissues, and the presence of the corresponding polypeptide and the (α(II))2β2 tetramer was demonstrated in cultured human WI-38 and HT-1080 cells. The type II tetramer was found to represent about 30% of the total prolyl 4-hydroxylase in these cells and about 5–15% in various chick embryo tissues. The results of coexpression in insect cells argued strongly against the formation of a mixed α(I)α(II)β2 tetramer. PDI/β polypeptide containing a histidine tag in its N terminus was found to form prolyl 4-hydroxylase tetramers as readily as the wild-type PDI/β polypeptide, and histidine-tagged forms of prolyl 4-hydroxylase appear to offer an excellent source for a simple large scale purification of the recombinant enzyme. The properties of the purified human type II enzyme were very similar to those of the type I enzyme, but theK i of the former for poly(l-proline) was about 200–1000 times that of the latter. In agreement with this, a minor difference, about 3–6-fold, was found between the two enzymes in the K m values for three peptide substrates. The existence of two forms of prolyl 4-hydroxylase in human cells raises the possibility that mutations in one enzyme form may not be lethal despite the central role of this enzyme in the synthesis of all collagens. Prolyl 4-hydroxylase (proline hydroxylase, EC 1.14.11.2) catalyzes the hydroxylation of proline in -Xaa-Pro-Gly- triplets in collagens and other proteins with collagen-like sequences. The enzyme plays a central role in the synthesis of all collagens, as the 4-hydroxyproline residues formed in the reaction are essential for the folding of the newly synthesized collagen polypeptide chains into triple helical molecules. The vertebrate enzyme is an α2β2tetramer in which the α subunits contribute to most parts of the two catalytic sites (for reviews, see Refs. 1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar, 3Prockop D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google Scholar). The β subunit is identical to the enzyme protein disulfide-isomerase (PDI, EC5.3.4.1) 1The abbreviations used are: PDI, protein disulfide-isomerase; His-PDI, PDI containing a histidine affinity tag in its N terminus; PAGE, polyacrylamide gel electrophoresis. and has PDI activity even when present in the prolyl 4-hydroxylase tetramer (4Pihlajaniemi T. Helaakoski T. Tasanen K. Myllylä R. Huhtala M.-L. Koivu J. Kivirikko K.I. EMBO J. 1987; 6: 643-649Crossref PubMed Scopus (330) Google Scholar, 5Koivu J. Myllylä R. Helaakoski T. Pihlajaniemi T. Tasanen K. Kivirikko K.I. J. Biol. Chem. 1987; 262: 6447-6449Abstract Full Text PDF PubMed Google Scholar, 6Parkkonen T. Kivirikko K.I. Pihlajaniemi T. Biochem. J. 1988; 256: 1005-1011Crossref PubMed Scopus (62) Google Scholar). The PDI polypeptide also has several other functions (1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar, 3Prockop D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google Scholar, 7Noiva R. Lennarz W.J. J. Biol. Chem. 1992; 267: 3553-3556Abstract Full Text PDF PubMed Google Scholar, 8Freedman R.B. Hirst T.R. Tuite M.F. Trends Biochem. Sci. 1994; 19: 331-336Abstract Full Text PDF PubMed Scopus (656) Google Scholar). Prolyl 4-hydroxylase had long been assumed to be of one type only, with no isoenzymes (1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar, 3Prockop D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google Scholar), but recently an isoform of the α subunit, termed the α(II) subunit, was cloned from mouse tissues (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar). Correspondingly, the previously known α subunit is now called the α(I) subunit. The α(II) subunit was found to form an (α(II))2β2 tetramer with the PDI/β subunit when the two polypeptides were coexpressed in insect cells. The properties of the new type II enzyme were found to be very similar to those of the type I tetramer, with the distinct difference that it was inhibited by poly(l-proline) only at very high concentrations (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar). The α subunit of prolyl 4-hydroxylase cloned from the nematodeCaenorhabditis elegans (10Veijola J. Koivunen P. Annunen P. Pihlajaniemi T. Kivirikko K.I. J. Biol. Chem. 1994; 269: 26746-26753Abstract Full Text PDF PubMed Google Scholar) has been found to have features of both types of mouse α subunit, suggesting that C. elegans may have only one type of α subunit (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar). This forms active prolyl 4-hydroxylase in insect cell coexpression experiments with either the C. elegans or the human PDI/β polypeptide, but surprisingly, the enzymes containing the C. elegans α subunit are αβ dimers (10Veijola J. Koivunen P. Annunen P. Pihlajaniemi T. Kivirikko K.I. J. Biol. Chem. 1994; 269: 26746-26753Abstract Full Text PDF PubMed Google Scholar, 11Veijola J. Annunen P. Koivunen P. Page A.P. Pihlajaniemi T. Kivirikko K.I. Biochem. J. 1996; 317: 721-729Crossref PubMed Scopus (31) Google Scholar). We report here that the existence of α(II) subunit mRNA is not limited to the mouse, as a corresponding mRNA is expressed in a variety of human tissues. All the data so far available on the existence of the type II prolyl 4-hydroxylase tetramer are based on insect cell coexpression experiments, but we now demonstrate that this enzyme is indeed present in cultured human fibroblasts and represents about 30% of their total prolyl 4-hydroxylase activity. We also studied whether the α(I) and α(II) subunits can form a mixed α(I)α(II)β2 tetramer, and whether any differences are found between the type I and II enzymes in their K m values for various peptide substrates, as the two mouse enzymes differ so markedly from each other with respect to inhibition by poly(l-proline). new affinity purification was that is based on the of a histidine tag in the N terminus of the PDI/β polypeptide, and this it to large of any form of the recombinant enzyme by very simple of a human with a for the mouse α(II) subunit (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar), as a one of the with as a of of and were The were by the K. S. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar) with or synthesized in an of of were and the were for both and was used to the human containing of from various human tissues was the in the The used either the human α(II) subunit or and T. Vuori K. Myllylä R. Kivirikko K.I. Pihlajaniemi T. Proc. Natl. Acad. Sci. U. S. A. 1989; PubMed Scopus Google Scholar) all of the human α(I) subunit. The was a for the human α(II) subunit, a was from the of The used were containing an and containing a reaction was the by the of and the were times as at for at for and at for The was with and enzymes to a that from to The was by with and The was with the to of the and termed was and to a was with and the was with the to of and the was termed The from and the from were to the of and the was termed the was with and the was to of the 1989; PubMed Scopus Google Scholar). histidine affinity tag was in the N terminus of the human PDI/β histidine were by reaction of the for the of the peptide in a for the human PDI/β polypeptide (4Pihlajaniemi T. Helaakoski T. Tasanen K. Myllylä R. Huhtala M.-L. Koivu J. Kivirikko K.I. EMBO J. 1987; 6: 643-649Crossref PubMed Scopus (330) Google Scholar). The was with and to insect cells were cultured in with at either as or in in The were into insect cells with a the The were and S. J. Scholar). The recombinant were termed α(II) and The human for the α(I) subunit, and human for the PDI/β polypeptide, have been previously K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1992; PubMed Scopus Google Scholar). insect cells were cultured as an enzyme tetramer, the or α(II) and the PDI/β or were used in a of or and when to an α(I)α(II)β2 tetramer, the and PDI/β were used in the or The cells were with a of and m in a of m and m and at for The were by or and for enzyme activity. The cell were in and by was with a to the human α(I) subunit or a to the mouse α(II) subunit. were by with recombinant α(I) or α(II) polypeptides that had been purified by The the α(I) and α(II) subunit both as and proteins from mouse, and but no between fibroblasts and cells were cultured in with at as The cells of were with a of m and m in a of m and to at and at for The were by by prolyl 4-hydroxylase activity was in of the and the type II enzyme activity in of the that had been poly(l-proline) and tissues from chick and chick were in a of m and to at and at for of the were used to the enzyme as The type II prolyl 4-hydroxylase from with the α(II) and PDI/β was purified by a of on a and two gel insect cells were with a of m and m in a of m and m with and and The was with a of m and m and to a with m and m was with the and the proteins were with an by of and of a of m m and The containing most of the prolyl 4-hydroxylase activity were by and to a and with a of m m and m of were and their at was were by and for prolyl 4-hydroxylase and a was and as for a gel on a and as of were by and for prolyl 4-hydroxylase activity. The type I and II prolyl 4-hydroxylase tetramers and the PDI/β polypeptide containing the histidine affinity tag were also purified by a of a affinity and a gel cells type I or type II prolyl 4-hydroxylase or the polypeptide were with a of m and in a m and and at for The was to a with a m and m was with the and the proteins were with a m and m containing the proteins were and to a gel and with a m and of were their at and was and were by containing the prolyl 4-hydroxylase tetramer or the PDI/β were and by and concentrations were with the protein to the the the type II prolyl 4-hydroxylase was on and a The was with in and the corresponding to the α(II) subunit was The was an protein Prolyl 4-hydroxylase activity was by a based either on the of or on the formation of in a protein of chains of chick type I K.I. Myllylä R. PubMed Scopus Google Scholar). K m values were by the of one in the presence of concentrations of the the concentrations of the other were R. Kivirikko K.I. J. Biochem. PubMed Scopus Google Scholar). The type II prolyl 4-hydroxylase tetramer was used as an enzyme source for theK m for the human α(II) subunit, a human was a for the mouse α(II) subunit (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar), as a which for the central of the was of the with as a of which were The of the corresponding mRNA are not but have been in the with and a polypeptide, a peptide of residues of the N terminus of the polypeptide that its is The of the mouse α(II) subunit was previously to be (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar), based on the of PubMed Scopus Google Scholar), but it now that this is as a also be with the The human human and mouse α(II) polypeptides are very similar in α(I) three All three polypeptides two sites for but the of the in the α(II) and α(I) subunits by residues The residues present in the mouse, and chick α(I) and the C. elegans α subunit are all in the human α(II) subunit, but the an which is also present in the mouse α(II) subunit The of the human α(II) subunit and to the of the human α(I) subunit and and to the of the mouse α(II) subunit. The of the subunits is not the of the two types of α subunit mRNA in various human tissues was studied by The of the for the human α(II) and α(I) subunits are and The mRNA for the α(II) subunit was found to be expressed in a variety of tissues, but distinct differences were found to the of that for the α(I) subunit, in that the of the was in the and whether the α(I) and α(II) subunits can form tetramers in to the type I and (α(II))2β2 type II tetramers (1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar, 3Prockop D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google Scholar, T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar), both types of α subunit were expressed in insect cells with the PDI/β The is inhibited by poly(l-proline) (1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar) and to poly(l-proline) affinity Kivirikko K.I. J. Biochem. PubMed Scopus Google Scholar). The (α(II))2β2 tetramer from the type I enzyme in that it is inhibited by poly(l-proline) only at very high concentrations (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar). can be that the type II enzyme not to poly(l-proline) a mixed α(I)α(II)β2 enzyme it be either to to to the presence of the α(I) subunit, or to insect cells were with for either the α(I) subunit or the α(II) subunit with for the PDI/β polypeptide, and a of cells was with all three The cells were and proteins were by the cells were with for either the α(I) subunit or the α(II) subunit with a for the PDI/β polypeptide, a type I or type II enzyme tetramer was the of these two types of tetramer identical and enzyme tetramer was formed when the cells were with all three with to the α(I) and α(II) subunits was used to between the types of tetramer. The to the α(I) subunit the type I tetramer but not the type II tetramer the to the α(II) subunit the type II tetramer but not the type I tetramer The type I tetramer to a poly(l-proline) affinity as no enzyme be in the and and be with poly(l-proline) and The type II tetramer was found in the and and no be from the with poly(l-proline) and the tetramer formed with for both types of α subunit was studied as a enzyme was in both the and the The in the be by the to the α(II) subunit but not that to α(I) the presence of α(I)α(II)β2 in the The in the be by the to the α(I) subunit but not to α(II) the presence of α(I)α(II)β2 in the The of the α(I)α(II)β2 tetramer be to the of of cells by three as we have recently that these cells can be by three A. Helaakoski T. J. S. Pihlajaniemi T. Kivirikko K.I. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). of human fibroblasts and cells were and proteins were by by with to the α(II) and α(I) subunits demonstrated corresponding to both types of enzyme tetramer were found in from both cell types of the which had been against known of both types of enzyme tetramer that the of type II enzyme is that of type I enzyme in both cell about 30% of total prolyl 4-hydroxylase not prolyl 4-hydroxylase the of the type I and type II enzyme was in from cell or as a The activity of the type II enzyme was by of poly(l-proline) affinity and the enzyme activity in The values were for and the type I enzyme activity was by the type II activity from the total activity. The type II enzyme activity was found to represent about 30% of the total enzyme activity in of human fibroblasts and HT-1080 cells not The corresponding in from of chick was and the in from of chick embryo tissues were in in in and in not the type II enzyme not to this enzyme not be purified by the affinity Kivirikko K.I. J. Biochem. PubMed Scopus Google Scholar, K.I. Myllylä R. 1987; PubMed Scopus Google Scholar) for type was purified an of and two gel The enzyme purified by this was as by of and the purification and a histidine affinity tag was to the N terminus of the PDI/β cells were with for either the α(I) or the α(II) subunit and the polypeptide, and the proteins were studied by types of α subunit were found to form an enzyme tetramer with the polypeptide and as as with the wild-type PDI/β polypeptide The were to a the was with the and the proteins were with enzyme tetramer was found in the and both types of enzyme tetramer and the and were present in the The enzyme tetramers and be from the polypeptide by gel which the was from dimers to The of both types of enzyme tetramer were also when by and of recombinant human type II and type I prolyl in from insect 4-hydroxylase are as of cell are as of cell in a new In agreement with data on mouse type II prolyl 4-hydroxylase (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar), the K m values of the human type II enzyme for and were identical to those of the human type I enzyme difference was found between the two human enzymes in inhibition by theK i values of the type II enzyme for about times those of the type I enzyme and those about times but differences were found between the human type II and type I enzymes in their K m values for three peptide substrates, in that all these values were times in the of the type II enzyme for the type I enzyme experiments not demonstrated that the type II enzyme, the type I enzyme, not any formation of when was used as a and the reaction were an as previously K.I. Myllylä R. PubMed Scopus Google m values of human type II and type I prolyl for and various peptide and K i values for or m in a new The data here that the existence of an mRNA for the α(II) subunit of prolyl 4-hydroxylase is not limited to the mouse (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar), as an mRNA for a similar α(II) subunit was also found in human tissues. the present data that the α(II) subunit is into the corresponding polypeptide in human cells. The α(II) subunit mRNA was found to be expressed in a variety of tissues, but distinct differences were found in the of the α(II) and α(I) subunit between tissues. of the of the two types of prolyl 4-hydroxylase tetramer by in cultured human WI-38 fibroblasts and HT-1080 cells that the type II tetramer represents about 30% of the total enzyme protein in these two cell Correspondingly, about 30% of the total prolyl 4-hydroxylase activity in from these two cell types was found in the of poly(l-proline) affinity suggesting that the represents about 30% of the total prolyl 4-hydroxylase activity. The type II prolyl 4-hydroxylase is also to be present in chick embryo tissues, as a of the total enzyme activity was found to the poly(l-proline) affinity in the of all the chick embryo tissues the of type II enzyme activity may be in chick embryo tissues in human about 5–15% of total prolyl 4-hydroxylase activity. This with that to at of the total prolyl 4-hydroxylase activity present in from chick is to a poly(l-proline) affinity Kivirikko K.I. J. Biochem. PubMed Scopus Google Scholar), and that at of the total prolyl 4-hydroxylase activity present in from chick embryo is inhibited by poly(l-proline) D.J. Kivirikko K.I. J. Biol. Chem. Full Text PDF PubMed Google Scholar). The present insect cell data strongly against the presence of a protein containing the α(I) and α(II) subunits in a is available on in the α subunits that are in the tetramer but the of the α which the of between the α(I) and α(II) subunits and elegans α subunit (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar, J. Koivunen P. Annunen P. Pihlajaniemi T. Kivirikko K.I. J. Biol. Chem. 1994; 269: 26746-26753Abstract Full Text PDF PubMed Google Scholar), are known to residues in the of all the to a catalytic A. Pihlajaniemi T. Kivirikko K.I. J. Biol. Chem. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar, J. Kivirikko K.I. EMBO J. PubMed Scopus Google Scholar). that the in tetramer that of the α(I) and α(II) subunits into the no is available on the in the α subunits that are for tetramer several that in the of the PDI/β subunit are to the of the polypeptide J. Annunen P. Koivunen P. Page A.P. Pihlajaniemi T. Kivirikko K.I. Biochem. J. 1996; 317: 721-729Crossref PubMed Scopus (31) Google Scholar, P. Helaakoski T. Annunen P. J. S. Pihlajaniemi T. Kivirikko K.I. Biochem. J. 1996; PubMed Scopus Google Scholar). The present data demonstrate that the N terminus of the PDI/β polypeptide is not for tetramer as the polypeptide was found to form an active prolyl 4-hydroxylase as readily as the wild-type PDI/β experiments have demonstrated that the polypeptide also forms an αβ with the C. elegans prolyl 4-hydroxylase α subunit. and K. The histidine-tagged forms of prolyl 4-hydroxylase appear to offer an excellent source of the enzyme for simple large scale purification in experiments as at has been as a with respect to the polypeptide of prolyl from all the vertebrate and an polypeptide for all prolyl (1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar, 3Prockop D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google Scholar). is that the human and mouse (9Helaakoski T. Annunen P. MacNeil I.A. Vuori K. Pihlajaniemi T. Kivirikko K.I. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4427-4431Crossref PubMed Scopus (90) Google Scholar) type II prolyl are inhibited by poly(l-proline) only at very high This of the type II enzyme with that for of prolyl 4-hydroxylase from the D.J. J. Biol. Chem. Full Text PDF PubMed Google Scholar) and for the recombinant C. 4-hydroxylase αβ (10Veijola J. Koivunen P. Annunen P. Pihlajaniemi T. Kivirikko K.I. J. Biol. Chem. 1994; 269: 26746-26753Abstract Full Text PDF PubMed Google Scholar, 11Veijola J. Annunen P. Koivunen P. Page A.P. Pihlajaniemi T. Kivirikko K.I. Biochem. J. 1996; 317: 721-729Crossref PubMed Scopus (31) Google Scholar). these that distinct differences are to in the of the peptide sites of various prolyl a was here between the K m values of the human type I and type II enzymes for three peptide the polypeptide which is the most used peptide for prolyl the which has been as a peptide for J. Biol. Chem. Full Text PDF PubMed Google Scholar), a protein that also 4-hydroxyproline (1Kivirikko K.I. Myllylä R. Pihlajaniemi T. FASEB J. 1989; 3: 1609-1617Crossref PubMed Scopus (258) Google Scholar, 2Kivirikko K.I. Myllylä R. Pihlajaniemi T. Harding J.J. Crabbe M.J.C. Post-Translational Modifications of Proteins. CRC Press, Boca Raton, FL1992: 1-51Google Scholar, 3Prockop D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google Scholar), and a for the enzyme. but differences were found between the type I and type II enzymes in these experiments, in that the K m values for all three peptide with the type II enzyme were about times those with the type I enzyme. these differences are very when with the at differences between their K i values for poly(l-proline). have been in the for types of collagen and for hydroxylase, a collagen to prolyl 4-hydroxylase in its catalytic properties D.J. Kivirikko K.I. Annu. Rev. Biochem. 1995; 64: 403-434Crossref PubMed Scopus (1379) Google K.I. PubMed Scopus Google Scholar, J. P. Kivirikko K.I. Myllylä R. 1992; PubMed Scopus Google Scholar, T. J. Kivirikko K.I. Myllylä R. PubMed Scopus Google Scholar, J. 1994; PubMed Scopus Google Scholar). mutations have been in the for the α(I) subunit of prolyl and to the central role of this enzyme in the synthesis of all collagens, mutations have been assumed to be The present data the presence of two of prolyl 4-hydroxylase α subunit in human tissues raises the that mutations in the for one type may not be cells are of the of the other type in when one type is We and for their
Annunen et al. (Tue,) studied this question.
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