protein beta-aspartate methyltransferase; protein L-isoaspartyl/D-aspartyl methyltransferase (PCMT1)

Function

• catalyzes methyl esterification of L-isoaspartyl & D-aspartyl residues in peptides & proteins that result from spontaneous decomposition of normal L-aspartyl (Asp) & L-asparaginyl (Asn) residues
• role in the repair &/or degradation of damaged proteins
• substrates include:
  • microtubule-associated protein 2
  • calreticulin
  • clathrin light chains a & b
  • ubiquitin carboxyl-terminal hydrolase isozyme L1
  • phosphatidylethanolamine-binding protein 1
  • stathmin
  • beta-synuclein
  • alpha-synuclein

S-adenosyl-L-methionine + protein L- isoaspartate
               <-->
S-adenosyl-L-homocysteine +
protein L-isoaspartate alpha-methyl ester

Structure

• monomer
• belongs to the L-isoaspartyl/D-aspartyl protein
• methyltransferase family

Compartment

cytoplasm

Alternative splicing

named isoforms=2

Polymorphism

• allele frequencies for polymorphism at codon 120 differ between ethnic groups (Ile-120 vs Val-120)
  • in Caucasians, Ile-120 is present at a frequency of 0.45, Val-120 is present at a frequency of 0.55
  • in Asians, Ile-120 is present at a frequency of 0.88, Val-120 is present at a frequency of 0.12
  • in Africans, Ile-120 is present at a frequency of 0.81 Val-120 is present at a frequency of 0.19
• Ile-120 variant has higher specific activity & thermostability than the Val-120 variant
• the Val-120 variant has a higher affinity for protein substrates

More general terms

• methyltransferase

Database

• UniProt: http://www.uniprot.org/uniprot/P22061.html
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=5110
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:5110
• OMIM: https://mirror.omim.org/entry/176851