IUBMB Enzyme Nomenclature


Accepted name: intermediate cleaving peptidase 55

Reaction: The enzyme cleaves the Pro36-Pro37 bond of cysteine desulfurase (EC removing three amino acid residues (Tyr-Ser-Pro) from the N-terminus after cleavage by mitochondrial processing peptidase.

Other name(s): Icp55; mitochondrial intermediate cleaving peptidase 55 kDa

Comments: Icp55 removes the destabilizing N-terminal amino acid residues that are left after cleavage by the mitochondrial processing peptidase, leading to the stabilisation of the substrate. The enzyme can remove single amino acids or a short peptide, as in the case of cysteine desulfurase (EC, where three amino acids are removed.

Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, PDB, CAS registry number:


1. Naamati, A., Regev-Rudzki, N., Galperin, S., Lill, R. and Pines, O. Dual targeting of Nfs1 and discovery of its novel processing enzyme, Icp55. J. Biol. Chem. 284 (2009) 30200-30208. [PMID: 19720832]

2. Vogtle, F.N., Wortelkamp, S., Zahedi, R.P., Becker, D., Leidhold, C., Gevaert, K., Kellermann, J., Voos, W., Sickmann, A., Pfanner, N. and Meisinger, C. Global analysis of the mitochondrial N-proteome identifies a processing peptidase critical for protein stability. Cell 139 (2009) 428-439. [PMID: 19837041]

[EC created 2011]

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