Carboxypeptidase Y (CPDY) is a glycoprotein exopeptidase of the acid and serine class.
History
CPDY was originally referred to as proteinase C by Hata et al. in 1967. In 1970, Hayashi et al. found that CPDY released C-terminal amino acids from peptides and determined it is inactivated by DFP at the active site serine residue, thus classifying it as a serine peptidase (Hayashi et al. 1970, and Mortensen et al. 2004).
Wolf and Fink (1975) first identified the structural gene for CPDY, which was later confirmed by Hemmings et al. (1981). In the 1980s, extensive work was done to better understand the signal sequence of CPDY and it was determined that the protein can be translocated without its amino-terminal sequence (Hemmings et al. 1981 and Blachly-Dyson and Stevens 1987). Throughout the 1990s, the carbohydrate contents of CPDY were studied (Ballou et al. 1990), and in 1994 the crystal structure was solved to a 2.8 Å resolution by Endrizzi et al..
Recent work has focused on transport of the nascent protein (Gharakhanian et al. 2011, Mukaiyama et al. 2010, and Burston et al. 2008) and inhibitory proteins (Gombault et al. 2009).
Composition
Unlike carboxypeptidases A and B, CPDY contains no metal ion. It is glycosylated at four positions, and contains 15% mannose. Some of the carbohydrate chains are phosphorylated (Trimble and Maley 1977, Hasilik and Tanner 1978, Hashimoto et al. 1981, Winther et al. 1991, and Mortensen et al. 2004). Each molecule of CPDY contains 4-5 diesterfied phosphates (Hashimoto et al. 1981).
The CPDY structure consists of fourteen a-helices, eleven strands of mixed ß-sheets, five disulfide bridges, and one free cysteine residue (Endrizziet al. 1994).
Molecular Characteristics
The mature chain of CPDY contains 421 amino acid residues. The gene, prc1, has been cloned and sequenced and encodes a prepro form of the enzyme (Stevens et al. 1986, Blachly-Dyson and Stevens 1987, Valls et al. 1987, and Mortensen et al. 2004).
