Serine Carboxypeptidase 1 (SCPEP1)

Scpep1 is a lysosomal matrix protein that was initially identified in a screen for genes induced by retinoic acid. it has been spotlighted by several proteome analyses of the lysosomal compartment, but its cellular function and properties remain unknown to date. Although Scpep1 shares notable homology and a number of structural hallmarks with the well-described lysosomal carboxypeptidase protective protein/cathepsin A, the purified recombinant 55 kDa precursor and the homogenates of Scpep1-overexpressing cells do not show proteolytic activity or increased serine carboxypeptidase activity towards artificial serine carboxypeptidase substrates. However, Scpep1-deficient mice were viable and fertile, and did not exhibit either lysosomal storage or reduced lysosomal SC activity under any tested condition.