Characterization of a secretase activity for placental leucine aminopeptidase.
Placental leucine aminopeptidase (P-LAP) is believed to play an important role in the inactivation of small regulatory peptides. P-LAP exists in both membrane-bound and soluble forms and cDNA cloning has demonstrated that P-LAP is a type II membrane protein, which means that its soluble form is released by a specific proteolytic cleavage. In this report, we studied this process in COS7 cells. Inhibitors of serine or aspartic proteases did not affect the secretion of P-LAP, while EDTA and 1,10-phenanthroline inhibited it. In addition, we transfected P-LAP expression vectors that have point mutations of the cleavage site or deletion of the juxtamembrane stalk. Point mutations of the cleavage site resulted in significantly lower secretion of P-LAP. On the contrary, the distance to cleavage site showed no relation to P-LAP secretion. These results suggest that P-LAP secretase has a metalloprotease activity which depends on the amino acid sequence of the cleavage site.
Iwase
A
A
Department of Obstetrics and Gynecology, Nagoya University School of Medicine, Nagoya, 466-8550, Japan.
Nomura
S
S
Mizutani
S
S
D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D001483:Base Sequence; D019556:COS Cells; D020134:Catalytic Domain / Q000235:genetics; D010122:Cystinyl Aminopeptidase / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D010920:Placenta / Q000201:enzymology*; D017354:Point Mutation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D012995:Solubility; D014162:Transfection
D017931:DNA Primers; D011994:Recombinant Proteins; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human