Identification of an alanine aminopeptidase in human maternal serum as a membrane-bound aminopeptidase N.
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Watanabe Y, Iwaki-Egawa S, Mizukoshi H, Fujimoto Y
Identification of an alanine aminopeptidase in human maternal serum as a membrane-bound aminopeptidase N.
Biol Chem Hoppe Seyler. 1995 Jul;376(7):397-400.
- PubMed ID
- 7576235 [ View in PubMed]
- 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.