Deletion of the Saccharomyces cerevisiae gene YOL008W, here referred to as COQ10, elicits a respiratory defect as a result of the inability of the mutant to oxidize NADH and succinate. Both activities are restored by exogenous coenzyme Q2. Respiration is also partially rescued by COQ2, COQ7, or COQ8/ABC1, when these genes are present in high copy. Unlike other coq mutants, all of which lack Q6, the coq10 mutant has near normal amounts of Q6 in mitochondria. Coq10p is widely distributed in bacteria and eukaryotes and is homologous to proteins of the “aromatic-rich protein family” Pfam03654 and to members of the START domain superfamily that have a hydrophobic tunnel implicated in binding lipophilic molecules such as cholesterol and polyketides. Analysis of coenzyme Q in polyhistidine-tagged Coq10p purified from mitochondria indicates the presence 0.032–0.034 mol of Q6/mol of protein. We propose that Coq10p is a Q6-binding protein and that in the coq10 mutant Q6 it is not able to act as an electron carrier, possibly because of improper localization. Deletion of the Saccharomyces cerevisiae gene YOL008W, here referred to as COQ10, elicits a respiratory defect as a result of the inability of the mutant to oxidize NADH and succinate. Both activities are restored by exogenous coenzyme Q2. Respiration is also partially rescued by COQ2, COQ7, or COQ8/ABC1, when these genes are present in high copy. Unlike other coq mutants, all of which lack Q6, the coq10 mutant has near normal amounts of Q6 in mitochondria. Coq10p is widely distributed in bacteria and eukaryotes and is homologous to proteins of the “aromatic-rich protein family” Pfam03654 and to members of the START domain superfamily that have a hydrophobic tunnel implicated in binding lipophilic molecules such as cholesterol and polyketides. Analysis of coenzyme Q in polyhistidine-tagged Coq10p purified from mitochondria indicates the presence 0.032–0.034 mol of Q6/mol of protein. We propose that Coq10p is a Q6-binding protein and that in the coq10 mutant Q6 it is not able to act as an electron carrier, possibly because of improper localization. Coenzyme Q (ubiquinone) is an essential electron carrier of the mitochondrial respiratory chain. Its main function is to accept electrons from the NADH- and succinate-coenzyme Q reductases and to donate them to the bc1 complex (1Hatefi Y. Annu. Rev. Biochem. 1985; 54: 1015-1069Crossref PubMed Google Scholar). Biosynthesis of coenzyme Q in eukaryotes occurs in mitochondria. The benzoquinone ring of coenzyme Q6 (Q6) of Saccharomyces cerevisiae has a polyprenyl side chain with six isoprenoid units (2Gloor U. Isler O. Morton R.A. Ruegg R. Wiss O. Helv. Chim. Acta. 1958; 41: 2357-2360Crossref Scopus (16) Google Scholar). At least nine yeast nuclear genes (COQ1–9) defined by nine complementation groups of a pet 3The abbreviations used are:pet mutantrespiratory deficient mutant of yeast with a mutation in a nuclear geneρo/– mutantrespiratory deficient mutant with either large deletions in or lacking mitochondrial DNAHPLChigh pressure liquid chromatographyNi-NTAnickel-nitrilotriacetic acid.3The abbreviations used are:pet mutantrespiratory deficient mutant of yeast with a mutation in a nuclear geneρo/– mutantrespiratory deficient mutant with either large deletions in or lacking mitochondrial DNAHPLChigh pressure liquid chromatographyNi-NTAnickel-nitrilotriacetic acid. mutant collection have been inferred to participate in the synthesis of Q6 based on the biochemical properties of the mutant mitochondria (3Tzagoloff A. Dieckmann C.L. Microbiol. Rev. 1990; 54: 211-225Crossref PubMed Google Scholar, 4Johnson A. Gin P. Marbois B.N. Hsieh E.J. Wu M. Barros M.H. Clarke C.F. Tzagoloff A. J. Biol. Chem. 2005; 280: 31397-31404Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar). Mutations in each of the nine genes block the NADH and succinate-cytochrome c reductase activities of mitochondria, which can be restored by addition of coenzyme Q2 (5Tzagoloff A. Akai A. Needleman R.B. J. Biol. Chem. 1975; 250: 8228-8235Abstract Full Text PDF PubMed Google Scholar). Additionally, coq mutants lack Q6 and coq3, coq4, coq5, coq6, coq7, coq8/abc1, and coq9 mutants accumulate 3-hexaprenyl-4-hydroxybenzoic acid, an early intermediate in Q6 biosynthesis (Refs. 4Johnson A. Gin P. Marbois B.N. Hsieh E.J. Wu M. Barros M.H. Clarke C.F. Tzagoloff A. J. Biol. Chem. 2005; 280: 31397-31404Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar and 6Clarke C.F. Williams W. Teruya J.H. J. Biol. Chem. 1991; 266: 16636-16644Abstract Full Text PDF PubMed Google Scholar, 7Marbois B.N. Clarke C.F. J. Biol. Chem. 1996; 271: 2995-3004Abstract Full Text Full Text PDF PubMed Scopus (151) Google Scholar, 8Barkovich R.J. Shtanko A. Shepherd J.A. Lee P.T. Myles D.C. Tzagoloff A. Clarke C.F. J. Biol. Chem. 1997; 272: 9182-9188Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar, 10Baba S.W. Belogrudov G.I. Lee J.C. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2004; 279: 10052-10059Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar, 12Do T.Q. Hsu A.Y. Jonassen T. Lee P.T. Clarke C.F. J. Biol. Chem. 2001; 276: 18161-18168Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar, 13Poon W.W. Do T.Q. Marbois B.N. Clarke C.F. Mol. Aspects Méd. 1997; 18: s121-s127Crossref PubMed Scopus (55) Google Scholar, see Ref. 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar for details of the pathway in yeast). Except for demethoxy-Q6, which accumulates in certain coq7 point mutants (7Marbois B.N. Clarke C.F. J. Biol. Chem. 1996; 271: 2995-3004Abstract Full Text Full Text PDF PubMed Scopus (151) Google Scholar, 14Padilla S. Jonassen T. Jimenez-Hidalgo M.A. Fernandez-Ayala D.J.M Lopez-Lluch G. Marbois B. Navas P. Clarke C.F. Santos-Ocana C. J. Biol. Chem. 2004; 279: 25995-26004Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar), other intermediates of the pathway are not detected in coq mutants (6Clarke C.F. Williams W. Teruya J.H. J. Biol. Chem. 1991; 266: 16636-16644Abstract Full Text PDF PubMed Google Scholar, 7Marbois B.N. Clarke C.F. J. Biol. Chem. 1996; 271: 2995-3004Abstract Full Text Full Text PDF PubMed Scopus (151) Google Scholar, 8Barkovich R.J. Shtanko A. Shepherd J.A. Lee P.T. Myles D.C. Tzagoloff A. Clarke C.F. J. Biol. Chem. 1997; 272: 9182-9188Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar, 10Baba S.W. Belogrudov G.I. Lee J.C. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2004; 279: 10052-10059Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar, 12Do T.Q. Hsu A.Y. Jonassen T. Lee P.T. Clarke C.F. J. Biol. Chem. 2001; 276: 18161-18168Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar). These observations indicate that the pathway is stringently regulated and/or that most of the intermediates are degraded when biosynthesis of Q6 is arrested. COQ gene products are located in, or are peripherally associated with the inner membrane of mitochondria (9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar, 10Baba S.W. Belogrudov G.I. Lee J.C. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2004; 279: 10052-10059Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar, 12Do T.Q. Hsu A.Y. Jonassen T. Lee P.T. Clarke C.F. J. Biol. Chem. 2001; 276: 18161-18168Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar, 13Poon W.W. Do T.Q. Marbois B.N. Clarke C.F. Mol. Aspects Méd. 1997; 18: s121-s127Crossref PubMed Scopus (55) Google Scholar, 14Padilla S. Jonassen T. Jimenez-Hidalgo M.A. Fernandez-Ayala D.J.M Lopez-Lluch G. Marbois B. Navas P. Clarke C.F. Santos-Ocana C. J. Biol. Chem. 2004; 279: 25995-26004Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar, 15Gin P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar) where they constitute a pathway that is similar to but diverges from the one in bacteria in at least two steps (16Olson R.E. Rudney H. Vitam. PubMed Scopus Google Scholar, Biochem. Google Scholar). respiratory deficient mutant of yeast with a mutation in a nuclear gene respiratory deficient mutant with either large deletions in or lacking mitochondrial high pressure liquid acid. respiratory deficient mutant of yeast with a mutation in a nuclear gene respiratory deficient mutant with either large deletions in or lacking mitochondrial high pressure liquid acid. the present a by mutants with a of YOL008W, which have The coq10 mutant is similar to other coq mutants in which of NADH and by mitochondria on addition of coenzyme Q2. Unlike the coq mutants, which lack Q6, the coq10 mutant here has normal of The of is a hydrophobic protein located in the inner membrane of mitochondria. is a of the large Pfam03654 of proteins protein A. R. S. M. PubMed Scopus Google Scholar). The of a of Y. S. T. R. B. T. 2005; PubMed Scopus Google Scholar) has a to the START domain Biochem. Full Text Full Text PDF PubMed Scopus Google Scholar), which the protein R.E. U. S. A. PubMed Scopus Google Scholar). on the presence in Coq10p of domain and the of Q6 in the purified propose that Coq10p is a Q6-binding which in the of Q6 to for electron and of yeast used in are in in yeast yeast yeast and with and of yeast R. of R. of 8Barkovich R.J. Shtanko A. Shepherd J.A. Lee P.T. Myles D.C. Tzagoloff A. Clarke C.F. J. Biol. Chem. 1997; 272: 9182-9188Abstract Full Text Full Text PDF PubMed Scopus (76) Google 4Johnson A. Gin P. Marbois B.N. Hsieh E.J. Wu M. Barros M.H. Clarke C.F. Tzagoloff A. J. Biol. Chem. 2005; 280: 31397-31404Abstract Full Text Full Text PDF PubMed Scopus (76) Google R. of in a of COQ2, COQ7, and and and by of with a yeast from nuclear partially with a of and and in the Tzagoloff A. PubMed Scopus Google Scholar). with of the by the of and PubMed Scopus Google Scholar). from yeast nuclear with and The the of and of with and in of gene and of and with and with and in C. J. J. 1985; PubMed Scopus Google Scholar). used to the with the two and The of the with and to a the yeast gene the The with the from and for the gene in and by the gene R.J. PubMed Scopus Google Scholar). of Coq10p with a and of a for Coq10p two and used to with a the and the The with a of and and the and of a Tzagoloff A. PubMed Scopus Google Scholar) with the and the of the used to the coq10 mutant to which the protein with six The gene by a all but the of in Tzagoloff A. 1991; PubMed Scopus Google Scholar) as to an to for the of protein from with the The protein in and partially purified on a Tzagoloff A. 1991; PubMed Scopus Google Scholar) and used to a in of a with the of The of with and with the as the The with a of and and a with the and M. of and by with and from of yeast mitochondrial protein and detected and by as A. Gin P. Marbois B.N. Hsieh E.J. Wu M. Barros M.H. Clarke C.F. Tzagoloff A. J. Biol. Chem. 2005; 280: 31397-31404Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar). The mitochondrial also by with pressure and of of or an pressure by a at to a in the at an of by or Q6, of Q6 and used to the of the used for T. J. Scholar). mitochondria from in to early by the of G. C. H. J. Mol. Biol. PubMed Scopus Google Scholar) that of used to of mitochondrial and of respiratory as (5Tzagoloff A. Akai A. Needleman R.B. J. Biol. Chem. 1975; 250: 8228-8235Abstract Full Text PDF PubMed Google Scholar). by the of R.J. J. Biol. Chem. Full Text PDF PubMed Google Scholar). and is a respiratory deficient mutant of the Deletion by with the in and by with in the and The respiratory defect of mutants is by to a that in gene are an early of of the mutant as a result of in nuclear Unlike most coq mutants, which a defect on (5Tzagoloff A. Akai A. Needleman R.B. J. Biol. Chem. 1975; 250: 8228-8235Abstract Full Text PDF PubMed Google Scholar, 6Clarke C.F. Williams W. Teruya J.H. J. Biol. Chem. 1991; 266: 16636-16644Abstract Full Text PDF PubMed Google Scholar, 7Marbois B.N. Clarke C.F. J. Biol. Chem. 1996; 271: 2995-3004Abstract Full Text Full Text PDF PubMed Scopus (151) Google Scholar, 8Barkovich R.J. Shtanko A. Shepherd J.A. Lee P.T. Myles D.C. Tzagoloff A. Clarke C.F. J. Biol. Chem. 1997; 272: 9182-9188Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar, 10Baba S.W. Belogrudov G.I. Lee J.C. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2004; 279: 10052-10059Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar, 12Do T.Q. Hsu A.Y. Jonassen T. Lee P.T. Clarke C.F. J. Biol. Chem. 2001; 276: 18161-18168Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar), and the other coq10 mutants on with a of of Q6 to has been to of coq mutants on T.Q. Hsu A.Y. Jonassen T. Lee P.T. Clarke C.F. J. Biol. Chem. 2001; 276: 18161-18168Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar). is by the of the and coq9 mutants in with The of is to in with Q6 properties of coq in a of mitochondria of and of the is because of the large of mutants in the The of nuclear pet mutants to accumulate large deletions in mitochondrial is when the are in genes for of the mitochondrial Tzagoloff A. J. 1985; PubMed Scopus Google Scholar). of mitochondrial protein synthesis in the coq10 mutant a normal of mitochondrial products that the of the mitochondrial not by a defect in The of in the mutant is with the of in the used for the The of and in the coq10 mutant is also in the c reductase and activities of mutant mitochondria mutants the c reductase of that in by The to be in a of the respiratory chain by the that the c reductase of the coq10 mutants be restored to of the by addition of exogenous coenzyme Q2 to the The Q2 is with of c reductase because of the used for the of mitochondria of mutants and the bc1 Coenzyme Q2 also restored NADH and in mitochondria of the coq10 mutant of NADH as a function of Q2 to the that the of the coq10 mutant similar to mutant that Q6 c reductase and activities of of c or of c in a of the coq10 mutant and of a mutant lacking Q6 as a function of Q2 in the The NADH of mitochondria as in the to The coq10 of Coenzyme Q6 in biochemical of the coq10 the of exogenous coenzyme Q2 for the NADH and are similar to the properties of other coq mutants to electron carrier (5Tzagoloff A. Akai A. Needleman R.B. J. Biol. Chem. 1975; 250: 8228-8235Abstract Full Text PDF PubMed Google Scholar). The of Q6 in the mutant by and of mitochondrial on a with an for of of The the presence of a with a with that of coenzyme Q6 The of as Q6 by which the presence in of the and coq10 mutant of the with a of Q6 at the and at a of Q6 P. J. Chem. PubMed Scopus (59) Google Scholar). The of Q6 in the mutant to be of mitochondrial protein The for the of Q6 in mitochondrial of and the coq10 are for the associated of from of purified mitochondria T. Clarke C.F. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar), and in of of the a as Both the mitochondrial from the and the coq10 for Q6 and and of coq10 and to when on a and as from of of to the mutant the that the nuclear in The nuclear of a used to a in the Tzagoloff A. PubMed Scopus Google Scholar). of with a of respiratory which COQ2, COQ7, or the genes the most in by COQ7, the least The NADH in mitochondria also in the with the of and in the with the of the either on a or nuclear not on the as as the that the COQ genes not have the mutation respiratory to the of the mutant on when COQ2, COQ7, and on a in that the is because of a gene for synthesis of Q6 is by the Q6 of in mitochondria of the with on the also a of mitochondrial as of the coq10 mutant with of the coq10 by a of the protein indicates that Coq10p in groups bacteria and Coq10p is a of the large START superfamily B. C. PubMed Scopus Google Scholar) that is of and other proteins of function such as members of the protein START proteins are defined as a not binding of the B. C. PubMed Scopus Google Scholar), from to a START proteins lipophilic and have been to be in and and to J. R. J. Biochem. PubMed Scopus Google Scholar, H. T. T. H. M. H. Y. T. M. 1997; Google Scholar). that the gene for a of yeast the in a yeast and for complementation of the yeast coq10 The of the yeast and by of of the yeast mutant on by and of Coq10p used to the protein in a protein of in mitochondria. protein in the coq10 mutant and in the mutant a of at the the of the protein as Coq10p with a purified from yeast mitochondria The of protein with the at that the of the constitute a mitochondrial that is Coq10p detected in the of proteins not Coq10p is a hydrophobic protein that is in the membrane of mitochondria by or by with but is by that it is an membrane protein is also by which indicates at least Coq10p is an inner membrane protein the is from lack of to in mitochondria and in the lacking an membrane of mitochondria to by from the of the is also by the of as a result of the of but not mitochondria. is an inner membrane protein the Shtanko A. Tzagoloff A. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google Scholar). The protein in mitochondria and the of the inner membrane in the indicates that Coq10p is the from mitochondria with the protein which has a of At present have to indicate Coq10p is a or Coq10p not with either or but with which is distributed in of Coenzyme Q in the coq10 that block coenzyme Q biosynthesis the of a of of pathway P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar, A.Y. Do T.Q. Lee P.T. Clarke C.F. Biophys. Acta. PubMed Scopus (66) Google Scholar). these proteins are also in the coq10 mitochondrial proteins by and with and The that the coq10 mutant has of but not of also in the mutant but not to the as is similar to that in mutants from the complementation groups to be Q6 deficient P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar). the on a high and restored to in also a of and in the in which the nuclear of the mutant with on a high not the of either or Analysis of Q6 in presence of a START domain in Coq10p it of to it is a Q6-binding protein. Coq10p purified from mitochondria of a coq10 mutant with a gene as to the protein with six at the the coq10 mutant when from an or in by the gene indicates that the presence of the not the of the protein. The protein purified from the of mitochondria with in the presence of of the in the on and at high of purified of by of the on a with the but of protein. of the protein and for Q6 by Q6 present in with as with the from a The of Q6 with to be 0.032–0.034 mol of Q6/mol of of the of Coq10p in mitochondria to amounts of purified that is or of of mitochondrial protein is of the mitochondrial of the for of mitochondrial protein. to a when the protein is from the high Deletion of of S. cerevisiae a that mitochondrial NADH and activities are in coq10 mutants but that activities are by addition of Q2 to the is a of mutants in Q6 synthesis (5Tzagoloff A. Akai A. Needleman R.B. J. Biol. Chem. 1975; 250: 8228-8235Abstract Full Text PDF PubMed Google Scholar). Unlike other coq mutants, which are deficient in Q6 A. Gin P. Marbois B.N. Hsieh E.J. Wu M. Barros M.H. Clarke C.F. Tzagoloff A. J. Biol. Chem. 2005; 280: 31397-31404Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 6Clarke C.F. Williams W. Teruya J.H. J. Biol. Chem. 1991; 266: 16636-16644Abstract Full Text PDF PubMed Google Scholar, 7Marbois B.N. Clarke C.F. J. Biol. Chem. 1996; 271: 2995-3004Abstract Full Text Full Text PDF PubMed Scopus (151) Google Scholar, 8Barkovich R.J. Shtanko A. Shepherd J.A. Lee P.T. Myles D.C. Tzagoloff A. Clarke C.F. J. Biol. Chem. 1997; 272: 9182-9188Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar, 10Baba S.W. Belogrudov G.I. Lee J.C. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2004; 279: 10052-10059Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar, 12Do T.Q. Hsu A.Y. Jonassen T. Lee P.T. Clarke C.F. J. Biol. Chem. 2001; 276: 18161-18168Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar, 13Poon W.W. Do T.Q. Marbois B.N. Clarke C.F. Mol. Aspects Méd. 1997; 18: s121-s127Crossref PubMed Scopus (55) Google Scholar, 14Padilla S. Jonassen T. Jimenez-Hidalgo M.A. Fernandez-Ayala D.J.M Lopez-Lluch G. Marbois B. Navas P. Clarke C.F. Santos-Ocana C. J. Biol. Chem. 2004; 279: 25995-26004Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar, 15Gin P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar, R.E. Rudney H. Vitam. PubMed Scopus Google Scholar), the coq10 mutant in normal of Q6 in mitochondria. Coq10p from for Q6 biosynthesis Coq10p is a membrane protein located in the inner The of the protein by are in the protein. is a mitochondrial that is Coq10p is to in that it the is similar to all the other that function in Q6 biosynthesis in yeast (9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar, 10Baba S.W. Belogrudov G.I. Lee J.C. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2004; 279: 10052-10059Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar, 15Gin P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar). of coq mutants are also by the coq10 (6Clarke C.F. Williams W. Teruya J.H. J. Biol. Chem. 1991; 266: 16636-16644Abstract Full Text PDF PubMed Google Scholar), (9Belogrudov G.I. Lee P.T. Jonassen T. Hsu A.Y. Gin P. Clarke C.F. Arch. Biochem. Biophys. 2001; 392: 48-58Crossref PubMed Scopus (54) Google Scholar), and R.J. Shtanko A. Shepherd J.A. Lee P.T. Myles D.C. Tzagoloff A. Clarke C.F. J. Biol. Chem. 1997; 272: 9182-9188Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar) have been to be for Q6 and as and Ref. 11Gin P. Hsu A.Y. Rothman S.C. Jonassen T. Lee P.T. Tzagoloff A. Clarke C.F. J. Biol. Chem. 2003; 278: 25308-25316Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar for the of these proteins indicates a large of and of but not in the coq10 is similar to has been for mutants in the coq genes P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar). The of in a coq gene on the of other coq gene products that of these proteins either on or on the presence of one or intermediates of the pathway P. Clarke C.F. J. Biol. Chem. 2005; 280: 2676-2681Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar). that be a of a complex B. Gin P. W.W. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2005; 280: Full Text Full Text PDF PubMed Scopus Google Scholar). here that Coq10p as a or is with other is by the of Coq10p the Coq10p or on is distributed in the of The of Coq10p with that of is or of an of the two proteins be at The presence of normal amounts of Q6 the large of that the mitochondrial of the protein is is for Q6 COQ2, COQ7, and are high of the coq10 when present on a is the most of the The of by on with an in the mitochondrial of and and a of mitochondrial of also a in the mitochondrial of These observations indicate that the of Coq10p can be to by normal of Q6 in mitochondria. for the of in of the the NADH and in the mutant to of indicates that the of Coq10p not the of the mitochondria to oxidize and Q6 and to the of the mutant by of with Q6, or by the mitochondrial of addition to the from with the also and These genes not of the coq10 mutant on that the are not in Q6 Coq10p is homologous to members of the Pfam03654 protein the Y. S. T. R. B. T. 2005; PubMed Scopus Google Scholar). protein of function has a similar to the cholesterol protein R.E. U. S. A. PubMed Scopus Google Scholar). The has a hydrophobic tunnel of one cholesterol of the and the has to to to the binding Y. S. T. R. B. T. 2005; PubMed Scopus Google Scholar, R.E. U. S. A. PubMed Scopus Google Scholar). is that of the six to be for are in and Coq10p The presence of binding in Coq10p that protein and coenzyme is by the presence of Q6 in purified of The of Q6 is not with the protein. the and of the of it is that most of the Q6 the The of Q6 associated with also be because of the that the protein purified from a of Coq10p is not a of the bc1 complex it is to function in the of respiratory The to the and Q reductase of of which have Coq10p be a for Q6 a high complex other B. Gin P. W.W. Lee P.T. Strahan J. Shepherd J.N. Clarke C.F. J. Biol. Chem. 2005; 280: Full Text Full Text PDF PubMed Scopus Google Scholar). Coq10p function in Q6 from of synthesis to the of the respiratory chain where it is function of Coq10p be to coenzyme Q from the to the bc1 complex electron in of the mitochondrial Coq10p which to be of that of Q6 and at least of most of the respiratory chain.
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