Positional proteomics identification of the natural substrates of cytosolic carboxypeptidases

Cytosolic carboxypeptidases (CCPs) constitute a new subfamily of M14 metallocarboxypeptidases associated to axonal regeneration and neuronal degeneration, amongst others. CCPs are deglutamylating enzymes, able to catalyze the shortening of polyglutamate side-chains and the gene-encoded C-termini of tubulin, telokin and myosin light chain kinase. The functions of these enzymes are not entirely understood, in part due to lack of information about C-terminal protein processing in the cell and its functional implications. By means of C-terminal COFRADIC, a positional proteomics approach, we searched for cellular substrates targets of CCP1, the most relevant member of this family. We here identified 7 new putative CCP1 protein substrates, including ribosomal proteins, translation factors and high mobility group proteins.