title: Identification of an alanine aminopeptidase in human maternal serum as a membrane-bound aminopeptidase N.
abstract: In addition to cystine aminopeptidase (oxytocinase) alanine aminopeptidase is present at high levels in the serum of pregnant women. In this study we compared the enzyme with membrane-bound aminopeptidase N purified from human placenta. Comparison of catalytic and immunological properties and N-terminal sequence analyses revealed that the enzymes were differentially processed derivatives of the same protein, and that the N-terminal 68 residues of aminopeptidase N were deleted in the alanine aminopeptidase. The deleted sequence contains a small cytoplasmic region, a hydrophobic transmembrane domain and a junctional domain. These results suggest that the enzyme may be released into the maternal circulation as a result of lacking these three domains.
authors.affiliation: Department of Clinical Biochemistry, Hokkaido Institute of Pharmaceutical Sciences, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: S
authors.initials: S
authors.lastname: Iwaki-Egawa
authors.forename: H
authors.initials: H
authors.lastname: Mizukoshi
authors.forename: Y
authors.initials: Y
authors.lastname: Fujimoto
mesh_terms: D000595:Amino Acid Sequence; D018826:CD13 Antigens / Q000097:blood* / Q000737:chemistry / Q000276:immunology; D002384:Catalysis; D002462:Cell Membrane / Q000201:enzymology; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy / Q000097:blood*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D018826:CD13 Antigens