Cytoplasmic dipeptidylpeptidase iv from human t-cells

摘要

A purified enzyme characterized as follows: (a) it is present in the cytoplasm of Jurkat cells; (b) it exhibits specific post-prolyl dipeptidase enzymatic activity; (c) it is structurally distinct from CD26; (d) its dipeptidase activity is reduced more than ten-fold when acting at a pH of 5.5, compared to a pH of 6.8; (e) it has an apparent molecular weight of about 60kD on SDS-PAGE; (f) it contains the amino acid sequence NAFTVLAMMDYPY [GT148], and DLFLOGAYDTVR [GT103]; (g) it contains the amino acid sequence LDHFNFER [GT85], and DVTADFEGOSPK [GT69]; (h) it occurs naturally in T-cells of healthy humans; (i) it naturally protects human T-cells in which it occurs from apoptosis; (j) it is multimeric; and (k) it has an isoelectric point of 4.5-5.5, as measured by ion-exchange.