IUBMB Enzyme Nomenclature


Accepted name: signal peptidase I

Reaction: Cleavage of hydrophobic, N-terminal signal or leader sequences

Other names: leader peptidase I; signal proteinase; Escherichia coli leader peptidase; eukaryotic signal peptidase; eukaryotic signal proteinase; leader peptidase; leader peptide hydrolase; leader proteinase; signal peptidase; pilin leader peptidase; SPC; prokaryotic signal peptidase; prokaryotic leader peptidase; HOSP; prokaryotic signal proteinase; propeptidase; PuIO prepilin peptidase; signal peptide hydrolase; signal peptide peptidase; signalase; bacterial leader peptidase 1; pilin leader peptidase

Comments: The enzyme is found in bacterial membranes and in chloroplast thylakoid membranes. Unaffected by inhibitors of most serine peptidases, but site-directed mutagenesis implicates a Ser/Lys catalytic dyad in activity [1,3]. Hydrolyses a single bond -AlaAla- in M13 phage procoat protein, producing free signal peptide and coat protein. Formerly included in EC Eukaryote signal peptidases that may have somewhat different specificity are known from the endoplasmic reticulum membrane [4] and mitochondrial inner membrane [2]. Type example of peptidase family S26

Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, PDB, CAS registry number: 65979-36-4


1. Black, M.T. Evidence that the catalytic activity of prokaryote leader peptidase depends upon the operation of a serine-lysine catalytic dyad. J. Bacteriol. 175 (1993) 4957-4961. [PMID: 8394311]

2. Nunnari, J., Fox, T.D. and Walter, P. A mitochondrial protease with two catalytic subunits of nonoverlapping specificities. Science 262 (1993) 1997-2004

3. Tschantz, W.R., Sung, M., Delgado-Partin, V.M. and Dalbey, R.E. A serine and a lysine residue implicated in the catalytic mechanism of the Escherichia coli leader peptidase. J. Biol. Chem. 268 (1993) 27349-27354. [PMID: 8262975]

4. Lively, M.O., Newsome, A.L. and Nusier, M. Eukaryote microsomal signal peptidases. Methods Enzymol. 244 (1994) 301-314. [PMID: 7845216]

5. Tschantz, W.R. and Dalbey, R.E. Bacterial leader peptidase I. Methods Enzymol. 244 (1994) 285-301. [PMID: 7845215]

6. Chaal, B.K., Mould, R.M., Barbrook, A.C., Gray, J.C. and Howe, C.J. Characterization of a cDNA encoding the thylakoidal processing peptidase from Arabidopsis thaliana. Implications for the origin and catalytic mechanism of the enzyme. J. Biol. Chem. 273 (1998) 689-692. [PMID: 9422718]

7. Inoue, K., Baldwin, A.J., Shipman, R.L., Matsui, K., Theg, S.M. and Ohme-Takagi, M. Complete maturation of the plastid protein translocation channel requires a type I signal peptidase. J. Cell Biol. 171 (2005) 425-430. [PMID: 16275749]

[EC created 1984 as EC, transferred 1995 to EC]

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