Substrate specificity of human metallocarboxypeptidase D: Comparison of the two active carboxypeptidase domains
The positions indicated in human CPD correspond to key residues essential for the catalytic mechanism: His69, Glu72, Arg145, His198, Tyr248, and Glu270 (according to the bCPA1 numbering). Sp, indicates the location of the endogenous signal peptide on the N-terminus. Recombinant proteins correspond to C-terminal truncated forms of human CPD, which lack the C-terminal transmembrane anchor and the cytoplasmic tail. The mutations (i.e., Glu to Gln) performed to generate single point mutants for the CPD domain I (E350Q), domain II (E762Q) and a double mutant (E350Q/E762Q) are indicated. The black shaded box on the N-term of the recombinant proteins corresponds to the IgM secretion signal sequence and N-terminal Strep-Tag II fusion protein.