IUBMB Enzyme Nomenclature


Accepted name: helper-component proteinase

Reaction: Hydrolyses a GlyGly bond at its own C-terminus, commonly in the sequence -Tyr-Xaa-Val-GlyGly, in the processing of the potyviral polyprotein

Other names: HC-Pro

Comments: Known from many potyviruses. The helper component-proteinase of the tobacco etch virus is a multifunctional protein with several known activities: the N-terminal region is required for aphid transmission and efficient genome amplification, the central region is required for long-distance movement in plants, and the C-terminal domain has cysteine endopeptidase activity. Type example of peptidase family C6.

Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, PDB, CAS registry number: 124566-20-7


1. Kasschau, K.D. and Carrington, J.C. Requirement for HC-Pro processing during genome amplification of tobacco etch potyvirus. Virology 209 (1995) 268-273.

2. Verchot, J. Potyvirus helper component proteinase. In: Barrett, A.J., Rawlings, N.D. and Woessner, J.F. (Eds.), Handbook of Proteolytic Enzymes, Academic Press, London, 1998, pp. 677-679.

[EC created 2001]

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