Protein-S-isoprenylcysteine O-methyltransferase

ICMT
Identifiers
Symbol	ICMT
Pfam	PF04140
Pfam clan	CL0115
InterPro	IPR007269
OPM superfamily	344
OPM protein	4a2n
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

protein-S-isoprenylcysteine O-methyltransferase
Identifiers
EC number	2.1.1.100
CAS number	Template:CAS
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / EGO
Search PMC articles PubMed articles NCBI proteins

The isoprenylcysteine o-methyltransferase (EC 2.1.1.100) carries out carboyxl methylation of cleaved eukaryotic proteins that terminate in a CaaX motif. In Saccharomyces cerevisiae (Baker's yeast) this methylation is carried out by Ste14p, an integral endoplasmic reticulum membrane protein. Ste14p is the founding member of the isoprenylcysteine carboxyl methyltransferase (ICMT) family, whose members share significant sequence homology.

The enzyme catalyzes the chemical reaction

S-adenosyl-L-methionine + protein C-terminal S-farnesyl-L-cysteine $\rightleftharpoons$ S-adenosyl-L-homocysteine + protein C-terminal S-farnesyl-L-cysteine methyl ester

Thus, the two substrates of this enzyme are S-adenosyl methionine and protein C-terminal S-farnesyl-L-cysteine, whereas its two products are S-adenosylhomocysteine and protein C-terminal S-farnesyl-L-cysteine methyl ester.

References

This article incorporates text from the public domain Pfam and InterPro IPR007269