title: Aminopeptidase A activity of the murine B-lymphocyte differentiation antigen BP-1/6C3.
abstract: The predicted amino acid sequence of the cDNA encoding the murine B-lymphocyte differentiation antigen BP-1/6C3 suggested that it is a member of the zinc-dependent metalloprotease family, possibly an aminopeptidase related to aminopeptidase N [microsomal aminopeptidase; alpha-aminoacyl-peptide hydrolase (microsomal), EC 3.4.11.2]. In the present studies, we examined the enzymatic activity of this antigen. From brush border preparations of the small intestine, a rich source of many endopeptidases and exopeptidases, the BP-1 antibody selectively removed aminopeptidase A [APA; L-alpha-aspartyl(L-alpha-glutamyl)-peptide hydrolase, EC 3.4.11.7] activity. The APA activity of a panel of cell lines correlated in linear fashion with cell-surface levels of the BP-1/6C3 antigen. APA activity was demonstrated for the BP-1/6C3 antigen immunopurified from the pre-B-cell membrane. This activity was enhanced by alkaline earth metals such as Ca2+ and was abrogated by amastatin and angiotensin, which are known competitive inhibitors of APA. The data indicate that the murine BP-1/6C3 antigen is active APA, an enzyme that catalyzes specifically the removal of unsubstituted, N-terminal glutamic acid and aspartic acid residues from peptides.
authors.affiliation: Department of Pediatrics, University of Alabama, Birmingham.
authors.forename: Q
authors.initials: Q
authors.lastname: Wu
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: M D
authors.initials: MD
authors.lastname: Cooper
authors.forename: M
authors.initials: M
authors.lastname: Pierres
authors.forename: J P
authors.initials: JP
authors.lastname: Gorvel
mesh_terms: D000626:Aminopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D002460:Cell Line; D043384:Glutamyl Aminopeptidase; D007421:Intestine, Small / Q000201:enzymology; D007700:Kinetics; D008666:Metalloendopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008871:Microvilli / Q000201:enzymology; D008970:Molecular Weight; D013379:Substrate Specificity; D015032:Zinc / Q000378:metabolism
chemical_list: D000626:Aminopeptidases; D043384:Glutamyl Aminopeptidase; C062906:BP-1-6C3 antigen; D008666:Metalloendopeptidases; D015032:Zinc