Reaction: PCMT1 transfers CH3 from AdoMet to isoAsp to form MetAsp
- in pathway: Protein repair
Protein-L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1, PIMT EC 2.1.1.77) transfers the methyl group from S-adenosyl-L-methionine (AdoMet) to the alpha side-chain carboxyl group of L-isoaspartyl and D-aspartatyl amino acids (Murray & Clarke 1986, Johnson et al. 1987, Galletti et al. 1988, Lowenson & Clarke 1992, The resulting methyl ester (MetAsp) undergoes spontaneous transformation to L-succinimide, which spontaneously hydrolyses to generates L-aspartyl residues or L-isoaspartyl residues. This repair process helps to maintain overall protein integrity. When PCMT1 is not present in cells, the abnormal aspartyl residues accumulate. Pcmt1 knockout mice exhibit fatal progressive epilepsy (Yamamoto et al. 1998).
Reaction - small molecule participants:
MetAsp [cytosol]
AdoHcy [cytosol]
isoAsp [cytosol]
AdoMet [cytosol]
Reactome.org reaction link: R-HSA-5676966
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Reaction input - small molecules:
L-beta-isoaspartate residue
S-adenosyl-L-methionine zwitterion
Reaction output - small molecules:
N-methyl-D-aspartic acid
S-adenosyl-L-homocysteine zwitterion
Reactome.org link: R-HSA-5676966