Identification of the CD45-associated 116-kDa and 80-kDa Proteins as the α- and β-Subunits of α-Glucosidase II

CD45 is an abundant, highly glycosylated transmembrane protein-tyrosine phosphatase expressed on hematopoietic cells. Herein we demonstrate that two proteins of 116 kDa and 80 kDa copurify with CD45 from mouse T cells. Microsequence analysis of the 116-kDa protein revealed high similarity to an incomplete human open reading frame that has been suggested to correspond to the catalytic α-subunit of glucosidase II. We determined the nucleotide sequence of the mouse cDNA and observed that it encodes a protein product nearly identical to its human homologue and shares an active site consensus sequence with Family 31 glucosidases. Amino acid sequencing of the 80-kDa protein, followed by molecular cloning, revealed high homology to human and bovine cDNAs postulated to encode the β-subunit of glucosidase II. Antisera developed to the mouse β-subunit allowed us to demonstrate that the interaction between CD45 and glucosidase II can be reconstituted in vitro in an endoglycosidase H-sensitive manner. The strong interaction between glucosidase II and CD45 may provide a paradigm for investigating novel aspects of the biology of these proteins. CD45 is an abundant, highly glycosylated transmembrane protein-tyrosine phosphatase expressed on hematopoietic cells. Herein we demonstrate that two proteins of 116 kDa and 80 kDa copurify with CD45 from mouse T cells. Microsequence analysis of the 116-kDa protein revealed high similarity to an incomplete human open reading frame that has been suggested to correspond to the catalytic α-subunit of glucosidase II. We determined the nucleotide sequence of the mouse cDNA and observed that it encodes a protein product nearly identical to its human homologue and shares an active site consensus sequence with Family 31 glucosidases. Amino acid sequencing of the 80-kDa protein, followed by molecular cloning, revealed high homology to human and bovine cDNAs postulated to encode the β-subunit of glucosidase II. Antisera developed to the mouse β-subunit allowed us to demonstrate that the interaction between CD45 and glucosidase II can be reconstituted in vitro in an endoglycosidase H-sensitive manner. The strong interaction between glucosidase II and CD45 may provide a paradigm for investigating novel aspects of the biology of these proteins. CD45 is a high molecular mass (∼180-∼220 kDa) transmembrane protein-tyrosine phosphatase (PTP) 1The abbreviations used are: PTP, protein-tyrosine phosphatase; DOC, sodium deoxycholate; Endo, endoglycosidase; ER, endoplasmic reticulum; GII, glucosidase II; kb, kilobase(s); H-LAG, human lysosomal α-glucosidase; MHC, major histocompatibility complex; ORF, open reading frame; PAGE, polyacrylamide gel electrophoresis; PCR, polymerase chain reaction; RACE, rapid amplification of cDNA ends; RT, reverse transcriptase. 1The abbreviations used are: PTP, protein-tyrosine phosphatase; DOC, sodium deoxycholate; Endo, endoglycosidase; ER, endoplasmic reticulum; GII, glucosidase II; kb, kilobase(s); H-LAG, human lysosomal α-glucosidase; MHC, major histocompatibility complex; ORF, open reading frame; PAGE, polyacrylamide gel electrophoresis; PCR, polymerase chain reaction; RACE, rapid amplification of cDNA ends; RT, reverse transcriptase.expressed in abundance on all cells of hematopoietic lineage (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar). Although CD45 is encoded by a single gene, alternative splicing of the mRNA allows for the generation of at least eight distinct isoforms of the molecule based on variable usage of exons 4–6, which encode a region of the amino-terminal ectodomain. Of particular interest, and experimental utility, is the observation that these isoforms are expressed in a cell type-specific and differentiation stage-specific manner. The variable exon repertoire expressed by different isoforms is known to greatly influence the charge properties of CD45 since the region encoded by these exons contains multiple sites forO-linked glycosylation (2Thomas M.L. Annu. Rev. Immunol. 1989; 7: 339-369Crossref PubMed Google Scholar). CD45 also possesses 11–18 putative N-linked glycosylation sites, which are subject to cell-specific controls, conferring further microheterogeneity upon CD45 (3Pulido R. Sanchez-Madrid F. Eur. J. Immunol. 1990; 20: 2667-2671Crossref PubMed Scopus (35) Google Scholar). It has been estimated that approximately one third of the total molecular weight of mature CD45 is contributed by carbohydrates, which vary qualitatively and quantitatively depending on the particular cell and isoform(s) expressed (3Pulido R. Sanchez-Madrid F. Eur. J. Immunol. 1990; 20: 2667-2671Crossref PubMed Scopus (35) Google Scholar).The cytoplasmic domain of CD45 is identical among all isoforms and encodes two tandem PTP domains, at least one of which possesses intrinsic activity (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar). A series of studies in CD45-deficient cell lines (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar) and, more recently, in CD45 gene-disrupted mice (4Kishihara K. Penninger J. Wallace V.A. Kundig T.M. Kawai K. Wakeham A. Timms E. Pfeffer K. Ohashi P.S. Thomas M.L. Furlonger C. Paige C.J. Mak T.W. Cell. 1993; 74: 143-156Abstract PubMed Scopus Google J. J. PubMed Scopus Google Scholar) revealed that CD45 a of and in which CD45 to is by the activity of of the of protein-tyrosine (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar). the that been aspects of the biology of it is known are for the PTP activity of by the of the It is also in to its to CD45 in hematopoietic cells distinct and more its to which can be the and of CD45 is to with which it we a 116-kDa of that with CD45 in a of hematopoietic cells J. PubMed Scopus Google Scholar). We to protein with an protein of 80 Amino acid analysis of these followed by molecular cloning, has revealed that are the mouse of two proteins that copurify with glucosidase II activity from A. J. PubMed Scopus Google Scholar). The of the of these with CD45 may provide novel aspects of the biology of II is a that to the and J. PubMed Google J. J. PubMed Scopus Google Scholar) and is in the of N-linked to II in sequence glucosidase has the from the two R. Annu. Rev. PubMed Scopus Google Scholar). The activity of glucosidase II in the is by that of a which can a single to A. J. PubMed Scopus Google Scholar). The of these two has been for in a of proteins a to be by the C. A. A. 1994; PubMed Scopus Google A. J. 1994; PubMed Scopus Google A. Cell. PubMed Scopus Google A. A. J. PubMed Scopus Google Scholar). a to glucosidase II. the glucosidase II allows to with and by the it the of proteins from and allows for from the of allowed to glucosidase II and its activity J. Google PubMed Scopus Google Eur. J. PubMed Scopus Google Eur. J. PubMed Scopus Google PubMed Scopus Google Scholar). the molecular of revealed recently, the of analysis of two proteins that copurify a with glucosidase II activity from A. J. PubMed Scopus Google Scholar). We the of two mouse cDNAs that encode proteins that copurify with the transmembrane PTP, in T of these proteins kDa in kDa in is a molecule that we a transmembrane that with CD45 in a of hematopoietic cell lines J. PubMed Scopus Google Scholar). that the cDNA sequence encodes a protein with a mass of kDa that shares sequence with the product of an human that an and region the of these mouse and human proteins contains sequence to Family 31 a highly catalytic consensus with the that of a to cDNA in in the of glucosidase II activity A. J. PubMed Scopus Google that the protein encoded by cDNA is the catalytic of glucosidase II We also been to glucosidase II activity in CD45 and in in the of an to the catalytic it is to the activity that we is mouse cDNA the protein that we with CD45 and that with glucosidase II activity by kDa in kDa in shares high sequence with a human protein, K. J. R. 1989; PubMed Scopus Google and an bovine sequence The human cDNA in an to to be two major of 80 and based on gel J. 1990; PubMed Scopus Google Scholar). The to be a for J. 1990; PubMed Scopus Google in to the protein, which revealed to be the protein J. 1990; PubMed Scopus Google A. 1989; PubMed Scopus Google J. PubMed Google Scholar). recently, the protein one of proteins in the molecular mass to in to J. PubMed Scopus Google Scholar). with these in is a for molecule a on cells of the conferring an to proteins by a series of from the of of proteins with J. A. C. A. PubMed Scopus Google Scholar). to is the from the β-subunit of glucosidase based on the that and a and are to A. J. PubMed Scopus Google it is to these a of to the of molecule from analysis of its cDNA is the that possesses a sequence that is at the in the mouse protein in the human and proteins in the studies A. J. PubMed Scopus Google K. J. R. 1989; PubMed Scopus Google A. J. PubMed Scopus Google J. PubMed Scopus Google Scholar). the mature protein a transmembrane that the protein the in and among and is a sequence has been to with a that to from the and to the proteins J. 1993; PubMed Google Scholar). of the in proteins has been to the J. 1993; PubMed Google K. J. 1994; PubMed Google Scholar). has in with proteins a highly region that may at a proteins in a A. PubMed Scopus Google J. 1989; PubMed Scopus Google J. J. 1994; PubMed Google Scholar). also possesses a of acid that may two Rev. PubMed Scopus Google Scholar). been to in and may for by a on the protein J. 1993; PubMed Google K. J. 1994; PubMed Google Scholar). possesses a of and possesses A. J. PubMed Scopus Google Scholar). these are with in the with the by that the β-subunit of glucosidase II. We that the 80-kDa protein with and a major we that the 80-kDa protein can with glucosidase II activity in the of CD45 Although to be for catalytic A. J. PubMed Scopus Google PubMed Scopus Google J. 1993; PubMed Google Eur. J. PubMed Scopus Google it may be of the activity of the it may to the α-subunit in with the of the an protein observed to be in A. J. PubMed Scopus Google PubMed Scopus Google Eur. J. PubMed Scopus Google Scholar) and also the of to to the a protein J. PubMed Scopus Google Eur. J. PubMed Scopus Google Scholar). It is to that has been in the of the catalytic K. J. R. 1989; PubMed Scopus Google A. J. PubMed Scopus Google Scholar). the that may to a in cell it may to the of proteins by The for an of in a is J. PubMed Scopus Google we been to of protein in of cells from is are we to copurify glucosidase II with that the interaction between glucosidase II and CD45 is on high the that glucosidase II with CD45 that contains The for is that and with CD45 in the that with all CD45 is a highly we are to the that we are to copurify glucosidase II with the of these proteins with by that may be the in which glucosidase II with it is that we to copurify of that on molecule that with is also that may to novel aspects of CD45 of CD45 is highly in cell is revealed by a the of high on CD45 from K. J. PubMed Scopus Google Scholar). It has further been that in a approximately of total CD45 is in the J. J. PubMed Google Scholar). of cell with of CD45 to to an It is to that a novel of glucosidase II may be to a of in a It is the PTP activity of the cytoplasmic domain of CD45 may be to a in particular it is that the has been to to the endoplasmic Cell. PubMed Scopus Google Scholar). and phosphatase can J. PubMed Scopus Google Scholar). in of the that may is a in of by cells in CD45 J. PubMed Scopus Google Scholar) and that of of CD45 with in the of T cells to from E. J. Immunol. Google Scholar). of the between CD45 and glucosidase II may provide novel the of these CD45 is a high molecular mass (∼180-∼220 kDa) transmembrane protein-tyrosine phosphatase (PTP) 1The abbreviations used are: PTP, protein-tyrosine phosphatase; DOC, sodium deoxycholate; Endo, endoglycosidase; ER, endoplasmic reticulum; GII, glucosidase II; kb, kilobase(s); H-LAG, human lysosomal α-glucosidase; MHC, major histocompatibility complex; ORF, open reading frame; PAGE, polyacrylamide gel electrophoresis; PCR, polymerase chain reaction; RACE, rapid amplification of cDNA ends; RT, reverse transcriptase. 1The abbreviations used are: PTP, protein-tyrosine phosphatase; DOC, sodium deoxycholate; Endo, endoglycosidase; ER, endoplasmic reticulum; GII, glucosidase II; kb, kilobase(s); H-LAG, human lysosomal α-glucosidase; MHC, major histocompatibility complex; ORF, open reading frame; PAGE, polyacrylamide gel electrophoresis; PCR, polymerase chain reaction; RACE, rapid amplification of cDNA ends; RT, reverse transcriptase.expressed in abundance on all cells of hematopoietic lineage (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar). Although CD45 is encoded by a single gene, alternative splicing of the mRNA allows for the generation of at least eight distinct isoforms of the molecule based on variable usage of exons 4–6, which encode a region of the amino-terminal ectodomain. Of particular interest, and experimental utility, is the observation that these isoforms are expressed in a cell type-specific and differentiation stage-specific manner. The variable exon repertoire expressed by different isoforms is known to greatly influence the charge properties of CD45 since the region encoded by these exons contains multiple sites forO-linked glycosylation (2Thomas M.L. Annu. Rev. Immunol. 1989; 7: 339-369Crossref PubMed Google Scholar). CD45 also possesses 11–18 putative N-linked glycosylation sites, which are subject to cell-specific controls, conferring further microheterogeneity upon CD45 (3Pulido R. Sanchez-Madrid F. Eur. J. Immunol. 1990; 20: 2667-2671Crossref PubMed Scopus (35) Google Scholar). It has been estimated that approximately one third of the total molecular weight of mature CD45 is contributed by carbohydrates, which vary qualitatively and quantitatively depending on the particular cell and isoform(s) expressed (3Pulido R. Sanchez-Madrid F. Eur. J. Immunol. 1990; 20: 2667-2671Crossref PubMed Scopus (35) Google Scholar). The cytoplasmic domain of CD45 is identical among all isoforms and encodes two tandem PTP domains, at least one of which possesses intrinsic activity (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar). A series of studies in CD45-deficient cell lines (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar) and, more recently, in CD45 gene-disrupted mice (4Kishihara K. Penninger J. Wallace V.A. Kundig T.M. Kawai K. Wakeham A. Timms E. Pfeffer K. Ohashi P.S. Thomas M.L. Furlonger C. Paige C.J. Mak T.W. Cell. 1993; 74: 143-156Abstract PubMed Scopus Google J. J. PubMed Scopus Google Scholar) revealed that CD45 a of and in which CD45 to is by the activity of of the of protein-tyrosine (1Trowbridge I.S. Thomas M.L. Annu. Rev. Immunol. 1994; 12: 85-116Crossref PubMed Scopus (654) Google Scholar). the that been aspects of the biology of it is known are for the PTP activity of by the of the It is also in to its to CD45 in hematopoietic cells distinct and more its to which can be the and of CD45 is to with which it we a 116-kDa of that with CD45 in a of hematopoietic cells J. PubMed Scopus Google Scholar). We to protein with an protein of 80 Amino acid analysis of these followed by molecular cloning, has revealed that are the mouse of two proteins that copurify with glucosidase II activity from A. J. PubMed Scopus Google Scholar). The of the of these with CD45 may provide novel aspects of the biology of II is a that to the and J. PubMed Google J. J. PubMed Scopus Google Scholar) and is in the of N-linked to II in sequence glucosidase has the from the two R. Annu. Rev. PubMed Scopus Google Scholar). The activity of glucosidase II in the is by that of a which can a single to A. J. PubMed Scopus Google Scholar). The of these two has been for in a of proteins a to be by the C. A. A. 1994; PubMed Scopus Google A. J. 1994; PubMed Scopus Google A. Cell. PubMed Scopus Google A. A. J. PubMed Scopus Google Scholar). a to glucosidase II. the glucosidase II allows to with and by the it the of proteins from and allows for from the of allowed to glucosidase II and its activity J. Google PubMed Scopus Google Eur. J. PubMed Scopus Google Eur. J. PubMed Scopus Google PubMed Scopus Google Scholar). the molecular of revealed recently, the of analysis of two proteins that copurify a with glucosidase II activity from A. J. PubMed Scopus Google Scholar). We the of two mouse cDNAs that encode proteins that copurify with the transmembrane PTP, in T of these proteins kDa in kDa in is a molecule that we a transmembrane that with CD45 in a of hematopoietic cell lines J. PubMed Scopus Google Scholar). that the cDNA sequence encodes a protein with a mass of kDa that shares sequence with the product of an human that an and region the of these mouse and human proteins contains sequence to Family 31 a highly catalytic consensus with the that of a to cDNA in in the of glucosidase II activity A. J. PubMed Scopus Google that the protein encoded by cDNA is the catalytic of glucosidase II We also been to glucosidase II activity in CD45 and in in the of an to the catalytic it is to the activity that we is mouse cDNA the protein that we with CD45 and that with glucosidase II activity by kDa in kDa in shares high sequence with a human protein, K. J. R. 1989; PubMed Scopus Google and an bovine sequence The human cDNA in an to to be two major of 80 and based on gel J. 1990; PubMed Scopus Google Scholar). The to be a for J. 1990; PubMed Scopus Google in to the protein, which revealed to be the protein J. 1990; PubMed Scopus Google A. 1989; PubMed Scopus Google J. PubMed Google Scholar). recently, the protein one of proteins in the molecular mass to in to J. PubMed Scopus Google Scholar). with these in is a for molecule a on cells of the conferring an to proteins by a series of from the of of proteins with J. A. C. A. PubMed Scopus Google Scholar). to is the from the β-subunit of glucosidase based on the that and a and are to A. J. PubMed Scopus Google it is to these a of to the of molecule from analysis of its cDNA is the that possesses a sequence that is at the in the mouse protein in the human and proteins in the studies A. J. PubMed Scopus Google K. J. R. 1989; PubMed Scopus Google A. J. PubMed Scopus Google J. PubMed Scopus Google Scholar). the mature protein a transmembrane that the protein the in and among and is a sequence has been to with a that to from the and to the proteins J. 1993; PubMed Google Scholar). of the in proteins has been to the J. 1993; PubMed Google K. J. 1994; PubMed Google Scholar). has in with proteins a highly region that may at a proteins in a A. PubMed Scopus Google J. 1989; PubMed Scopus Google J. J. 1994; PubMed Google Scholar). also possesses a of acid that may two Rev. PubMed Scopus Google Scholar). been to in and may for by a on the protein J. 1993; PubMed Google K. J. 1994; PubMed Google Scholar). possesses a of and possesses A. J. PubMed Scopus Google Scholar). these are with in the with the by that the β-subunit of glucosidase II. We that the 80-kDa protein with and a major we that the 80-kDa protein can with glucosidase II activity in the of CD45 Although to be for catalytic A. J. PubMed Scopus Google PubMed Scopus Google J. 1993; PubMed Google Eur. J. PubMed Scopus Google it may be of the activity of the it may to the α-subunit in with the of the an protein observed to be in A. J. PubMed Scopus Google PubMed Scopus Google Eur. J. PubMed Scopus Google Scholar) and also the of to to the a protein J. PubMed Scopus Google Eur. J. PubMed Scopus Google Scholar). It is to that has been in the of the catalytic K. J. R. 1989; PubMed Scopus Google A. J. PubMed Scopus Google Scholar). the that may to a in cell it may to the of proteins by The for an of in a is J. PubMed Scopus Google we been to of protein in of cells from is are we to copurify glucosidase II with that the interaction between glucosidase II and CD45 is on high the that glucosidase II with CD45 that contains The for is that and with CD45 in the that with all CD45 is a highly we are to the that we are to copurify glucosidase II with the of these proteins with by that may be the in which glucosidase II with it is that we to copurify of that on molecule that with is also that may to novel aspects of CD45 of CD45 is highly in cell is revealed by a the of high on CD45 from K. J. PubMed Scopus Google Scholar). It has further been that in a approximately of total CD45 is in the J. J. PubMed Google Scholar). of cell with of CD45 to to an It is to that a novel of glucosidase II may be to a of in a It is the PTP activity of the cytoplasmic domain of CD45 may be to a in particular it is that the has been to to the endoplasmic Cell. PubMed Scopus Google Scholar). and phosphatase can J. PubMed Scopus Google Scholar). in of the that may is a in of by cells in CD45 J. PubMed Scopus Google Scholar) and that of of CD45 with in the of T cells to from E. J. Immunol. Google Scholar). of the between CD45 and glucosidase II may provide novel the of these II is a that to the and J. PubMed Google J. J. PubMed Scopus Google Scholar) and is in the of N-linked to II in sequence glucosidase has the from the two R. Annu. Rev. PubMed Scopus Google Scholar). The activity of glucosidase II in the is by that of a which can a single to A. J. PubMed Scopus Google Scholar). The of these two has been for in a of proteins a to be by the C. A. A. 1994; PubMed Scopus Google A. J. 1994; PubMed Scopus Google A. Cell. PubMed Scopus Google A. A. J. PubMed Scopus Google Scholar). a to glucosidase II. the glucosidase II allows to with and by the it the of proteins from and allows for from the The of allowed to glucosidase II and its activity J. Google PubMed Scopus Google Eur. J. PubMed Scopus Google Eur. J. PubMed Scopus Google PubMed Scopus Google Scholar). the molecular of revealed recently, the of analysis of two proteins that copurify a with glucosidase II activity from A. J. PubMed Scopus Google Scholar). We the of two mouse cDNAs that encode proteins that copurify with the transmembrane PTP, in T cells. The of these proteins kDa in kDa in is a molecule that we a transmembrane that with CD45 in a of hematopoietic cell lines J. PubMed Scopus Google Scholar). that the cDNA sequence encodes a protein with a mass of kDa that shares sequence with the product of an human that an and region the of these mouse and human proteins contains sequence to Family 31 a highly catalytic consensus with the that of a to cDNA in in the of glucosidase II activity A. J. PubMed Scopus Google that the protein encoded by cDNA is the catalytic of glucosidase II We also been to glucosidase II activity in CD45 and in in the of an to the catalytic it is to the activity that we is The mouse cDNA the protein that we with CD45 and that with glucosidase II activity by kDa in kDa in shares high sequence with a human protein, K. J. R. 1989; PubMed Scopus Google and an bovine sequence The human cDNA in an to to be two major of 80 and based on gel J. 1990; PubMed Scopus Google Scholar). The to be a for J. 1990; PubMed Scopus Google in to the protein, which revealed to be the protein J. 1990; PubMed Scopus Google A. 1989; PubMed Scopus Google J. PubMed Google Scholar). recently, the protein one of proteins in the molecular mass to in to J. PubMed Scopus Google Scholar). with these in is a for molecule a on cells of the conferring an to proteins by a series of from the of of proteins with J. A. C. A. PubMed Scopus Google Scholar). to is the from the β-subunit of glucosidase based on the that and a and are to A. J. PubMed Scopus Google Scholar). Although it is to these a of to the of molecule from analysis of its cDNA is the that possesses a sequence that is at the in the mouse protein in the human and proteins in the studies A. J. PubMed Scopus Google K. J. R. 1989; PubMed Scopus Google A. J. PubMed Scopus Google J. PubMed Scopus Google Scholar). the mature protein a transmembrane that the protein the in and among and is a sequence has been to with a that to from the and to the proteins J. 1993; PubMed Google Scholar). of the in proteins has been to the J. 1993; PubMed Google K. J. 1994; PubMed Google Scholar). has in with proteins a highly region that may at a proteins in a A. PubMed Scopus Google J. 1989; PubMed Scopus Google J. J. 1994; PubMed Google Scholar). also possesses a of acid that may two Rev. PubMed Scopus Google Scholar). been to in and may for by a on the protein J. 1993; PubMed Google K. J. 1994; PubMed Google Scholar). possesses a of and possesses A. J. PubMed Scopus Google Scholar). these are with in the with the by that the β-subunit of glucosidase II. We that the 80-kDa protein with and a major we that the 80-kDa protein can with glucosidase II activity in the of CD45 Although to be for catalytic A. J. PubMed Scopus Google PubMed Scopus Google J. 1993; PubMed Google Eur. J. PubMed Scopus Google it may be of the activity of the it may to the α-subunit in with the of the an protein observed to be in A. J. PubMed Scopus Google PubMed Scopus Google Eur. J. PubMed Scopus Google Scholar) and also the of to to the a protein J. PubMed Scopus Google Eur. J. PubMed Scopus Google Scholar). It is to that has been in the of the catalytic K. J. R. 1989; PubMed Scopus Google A. J. PubMed Scopus Google Scholar). the that may to a in cell it may to the of proteins by The for an of in a is J. PubMed Scopus Google we been to of protein in of cells from is are we to copurify glucosidase II with that the interaction between glucosidase II and CD45 is on high the that glucosidase II with CD45 that contains The for is that and with CD45 in the that with all CD45 is a highly we are to the that we are to copurify glucosidase II with the of these proteins with by that may be the in which glucosidase II with it is that we to copurify of that on molecule that with It is also that may to novel aspects of CD45 of CD45 is highly in cell is revealed by a the of high on CD45 from K. J. PubMed Scopus Google Scholar). It has further been that in a approximately of total CD45 is in the J. J. PubMed Google Scholar). of cell with of CD45 to to an It is to that a novel of glucosidase II may be to a of in a It is the PTP activity of the cytoplasmic domain of CD45 may be to a in particular it is that the has been to to the endoplasmic Cell. PubMed Scopus Google Scholar). and phosphatase can J. PubMed Scopus Google Scholar). in of the that may is a in of by cells in CD45 J. PubMed Scopus Google Scholar) and that of of CD45 with in the of T cells to from E. J. Immunol. Google Scholar). of the between CD45 and glucosidase II may provide novel the of these We for the and and cell lines and for with the We also the sequencing of the and the of of and to for of the