Carboxypeptidase A inhibitor

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Carboxypeptidase A inhibitor
PDB 4cpa EBI.jpg
refined crystal structure of the potato inhibitor complex of carboxypeptidase a at 2.5 angstroms resolution
Symbol CarbpepA_inh
Pfam PF02977
Pfam clan CL0096
InterPro IPR004231
SCOP 4cpa

In molecular biology, the carboxypeptidase A inhibitor family is a family of proteins which is represented by the well-characterised metallocarboxypeptidase A inhibitor (MCPI) from potatoes, which belongs to the MEROPS inhibitor family I37, clan IE. It inhibits metallopeptidases belonging to MEROPS peptidase family M14, carboxypeptidase A. In Russet Burbank potatoes, it is a mixture of approximately equal amounts of two polypeptide chains containing 38 or 39 amino acid residues. The chains differ in their amino terminal sequence only [1] and are resistant to fragmentation by proteases.[2] The structure of the complex between bovine carboxypeptidase A and the 39-amino-acid carboxypeptidase A inhibitor from potatoes has been determined at 2.5-Angstrom resolution.[3]

The potato inhibitor is synthesised as a precursor, having a 29 amino acid N-terminal signal peptide, a 27 amino acid pro-peptide, the 39 amino acid mature inhibitor region and a 7 amino acid C-terminal extension. The 7 amino acid C-terminal extension is involved in inhibitor inactivation and may be required for targeting to the vacuole where the mature active inhibitor accumulates.[4]

The N-terminal region and the mature inhibitor are weakly related to other solananaceous proteins found in this family, from potato, tomato and henbane, which have been incorrectly described as metallocarboxypeptidase inhibitors.[5]


  1. ^ Hass GM, Nau H, Biemann K, Grahn DT, Ericsson LH, Neurath H (March 1975). "The amino acid sequence of a carboxypeptidase inhibitor from potatoes". Biochemistry 14 (6): 1334–42. doi:10.1021/bi00677a036. PMID 1122280. 
  2. ^ Leary TR, Grahn DT, Neurath H, Hass GM (May 1979). "Structure of potato carboxypeptidase inhibitor: disulfide pairing and exposure of aromatic residues". Biochemistry 18 (11): 2252–6. doi:10.1021/bi00578a018. PMID 444453. 
  3. ^ Rees DC, Lipscomb WN (August 1980). "Structure of the potato inhibitor complex of carboxypeptidase A at 2.5-A resolution". Proc. Natl. Acad. Sci. U.S.A. 77 (8): 4633–7. doi:10.1073/pnas.77.8.4633. PMC 349899. PMID 6933511. 
  4. ^ Villanueva J, Canals F, Prat S, Ludevid D, Querol E, Aviles FX (November 1998). "Characterization of the wound-induced metallocarboxypeptidase inhibitor from potato. cDNA sequence, induction of gene expression, subcellular immunolocalization and potential roles of the C-terminal propeptide". FEBS Lett. 440 (1-2): 175–82. doi:10.1016/S0014-5793(98)01447-1. PMID 9862450. 
  5. ^ Molnar A, Lovas A, Banfalvi Z, Lakatos L, Polgar Z, Horvath S (June 2001). "Tissue-specific signal(s) activate the promoter of a metallocarboxypeptidase inhibitor gene family in potato tuber and berry". Plant Mol. Biol. 46 (3): 301–11. PMID 11488477. 

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This article incorporates text from the public domain Pfam and InterPro IPR004231