PUBLICATION
Carboxypeptidase O is a glycosylphosphatidylinositol-anchored intestinal peptidase with acidic amino acid specificity
- Authors
- Lyons, P.J., and Fricker, L.D.
- ID
- ZDB-PUB-110920-37
- Date
- 2011
- Source
- The Journal of biological chemistry 286(45): 39023-32 (Journal)
- Registered Authors
- Keywords
- carboxypeptidase, intestinal epithelium, metalloprotease, protease, zebrafish, glutamate carboxypeptidase
- MeSH Terms
-
- Animals
- Carboxypeptidases/genetics
- Carboxypeptidases/metabolism*
- Dietary Proteins/metabolism
- Dogs
- GPI-Linked Proteins/genetics
- GPI-Linked Proteins/metabolism*
- Glycosylphosphatidylinositols*
- Humans
- Hydrogen-Ion Concentration
- Intestines/enzymology*
- Intracellular Membranes/enzymology*
- Zebrafish/genetics
- Zebrafish/metabolism*
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism*
- PubMed
- 21921028 Full text @ J. Biol. Chem.
Citation
Lyons, P.J., and Fricker, L.D. (2011) Carboxypeptidase O is a glycosylphosphatidylinositol-anchored intestinal peptidase with acidic amino acid specificity. The Journal of biological chemistry. 286(45):39023-32.
Abstract
The first metallocarboxypeptidase (CP) was identified in pancreatic extracts more than 80 years ago and named carboxypeptidase A (CPA; now known as CPA1). Since that time, seven additional mammalian members of the CPA subfamily have been described, all of which are initially produced as proenzymes, activated by endoproteases, and remove either C-terminal hydrophobic or basic amino acids from peptides. Here we describe the enzymatic and structural properties of carboxypeptidase O (CPO), a previously uncharacterized and unique member of the CPA subfamily. Whereas all other members of the CPA subfamily contain an N-terminal prodomain necessary for folding, bioinformatics and expression of both human and zebrafish CPO orthologs revealed that CPO does not require a prodomain. CPO was purified by affinity chromatography, and the purified enzyme was able to cleave proteins and synthetic peptides with greatest activity toward acidic C-terminal amino acids, unlike other CPA-like enzymes. CPO displayed a neutral pH optimum and was inhibited by common metallocarboxypeptidase inhibitors as well as citrate. CPO was modified by attachment of a glycosylphosphatidylinositol membrane anchor to the C-terminus of the protein. Immunocytochemistry of MDCK cells stably expressing CPO showed localization to vesicular membranes in subconfluent cells and to the plasma membrane in differentiated cells. CPO is highly expressed in intestinal epithelial cells in both zebrafish and human. These results suggest CPO cleaves acidic amino acids from dietary proteins and peptides, thus complementing the actions of well-known digestive carboxypeptidases, CPA and CPB.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping