InterPro domain: IPR000682

Protein-L-isoaspartate(D-aspartate) O-methyltransferase ( 2.1.1.77 ) (PCMT) [ 1 ] (which is also known as L-isoaspartyl protein carboxyl methyltransferase) is an enzyme that catalyses the transfer of a methyl group from S-adenosylmethionine to the free carboxyl groups of D-aspartyl or L-isoaspartyl residues in a variety of peptides and proteins. The enzyme does not act on normal L-aspartyl residues L-isoaspartyl and D-aspartyl are the products of the spontaneous deamidation and/or isomerisation of normal L-aspartyl and L-asparaginyl residues in proteins. PCMT plays a role in the repair and/or degradation of these damaged proteins; the enzymatic methyl esterification of the abnormal residues can lead to their conversion to normal L-aspartyl residues. The SAM domain is present in most of these proteins.

1. Molecular phylogenetics of a protein repair methyltransferase. Comp. Biochem. Physiol. B, Biochem. Mol. Biol. 117, 379-85