The isoprenylcysteine o-methyltransferase () carries out carboyxl methylation of cleaved eukaryotic proteins that terminate in a CaaX motif. In Saccharomyces cerevisiae, 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 [].This entry also includes ICMT from Methanosarcina acetivorans (). It comprises a core of five transmembrane α-helices and a cofactor-binding pocket enclosed within a highly conserved C-terminal catalytic subdomain [].
