EC - Signal peptidase I

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IntEnz Enzyme Nomenclature


Accepted name:
signal peptidase I
Other names:
Escherichia coli leader peptidase
PuIO prepilin peptidase
bacterial leader peptidase 1
eukaryotic signal peptidase
eukaryotic signal proteinase
leader peptidase
leader peptidase I
leader peptide hydrolase
leader proteinase
pilin leader peptidase
prokaryotic leader peptidase
prokaryotic signal peptidase
prokaryotic signal proteinase
signal peptidase
signal peptide hydrolase
signal peptide peptidase
signal proteinase
SPase I
phage-procoat-leader peptidase
bacterial leader peptidase I
Systematic name:



Present in the inner membrane of Escherichia coli. 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 -Ala┼Ala- 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

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , MEROPS , UniPathway
Protein domains and families: PROSITE:PDOC00418
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004252
CAS Registry Number: 65979-36-4
UniProtKB/Swiss-Prot: (138) [show] [UniProt]


  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 : 4957-4961 (1993). [PMID: 8394311]
  2. Nunnari, J., Fox, T.D. and Walter, P.
    A mitochondrial protease with two catalytic subunits of nonoverlapping specificities.
    Science 262 : 1997-2004 (1993). [PMID: 8266095]
  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 : 27349-27354 (1993). [PMID: 8262975]
  4. Lively, M.O., Newsome, A.L. and Nusier, M.
    Eukaryote microsomal signal peptidases.
    Methods Enzymol. 244 : 301-314 (1994). [PMID: 7845216]
  5. Tschantz, W.R. and Dalbey, R.E.
    Bacterial leader peptidase I.
    Methods Enzymol. 244 : 285-301 (1994). [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 : 689-692 (1998). [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 : 425-430 (2005). [PMID: 16275749]

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