Three classes of protein carboxyl methyltransferases, distinguished by their methyl-acceptor substrate specificity, have been found in prokaryotic and eukaryotic cells. The type II enzyme catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to the free carboxyl groups of D-aspartyl and L-isoaspartyl residues. These methyl-accepting residues result from the spontaneous deamidation, isomerization, and racemization of normal L-aspartyl and L-asparaginyl residues and represent sites of covalent damage to aging proteins PCMT1 (EC 2.1.1.77) is a protein repair enzyme that initiates the conversion of abnormal D-aspartyl and L-isoaspartyl residues to the normal L-aspartyl form.[supplied by OMIM][7]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^MacLaren DC, O'Connor CM, Xia YR, Mehrabian M, Klisak I, Sparkes RS, Clarke S, Lusis AJ (Feb 1993). "The L-isoaspartyl/D-aspartyl protein methyltransferase gene (PCMT1) maps to human chromosome 6q22.3-6q24 and the syntenic region of mouse chromosome 10". Genomics. 14 (4): 852–6. doi:10.1016/S0888-7543(05)80104-1. PMID1478665.852-6&rft.date=1993-02&rft_id=info:doi/10.1016/S0888-7543(05)80104-1&rft_id=info:pmid/1478665&rft.aulast=MacLaren&rft.aufirst=DC&rft.au=O'Connor, CM&rft.au=Xia, YR&rft.au=Mehrabian, M&rft.au=Klisak, I&rft.au=Sparkes, RS&rft.au=Clarke, S&rft.au=Lusis, AJ&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
^DeVry CG, Clarke S (Jun 1999). "Assignment of the protein L-isoaspartate (D-aspartate) O-methyltransferase gene (PCMT1) to human chromosome bands 6q24→q25 with radiation hybrid mapping". Cytogenet Cell Genet. 84 (1–2): 130–1. doi:10.1159/000015239. PMID10343128. S2CID38976877.1–2&rft.pages=130-1&rft.date=1999-06&rft_id=https://api.semanticscholar.org/CorpusID:38976877#id-name=S2CID&rft_id=info:pmid/10343128&rft_id=info:doi/10.1159/000015239&rft.aulast=DeVry&rft.aufirst=CG&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
MacLaren DC, Kagan RM, Clarke S (1992). "Alternative splicing of the human isoaspartyl protein carboxyl methyltransferase RNA leads to the generation of a C-terminal -RDEL sequence in isozyme II". Biochem. Biophys. Res. Commun. 185 (1): 277–83. doi:10.1016/S0006-291X(05)80987-8. PMID1339271.277-83&rft.date=1992&rft_id=info:doi/10.1016/S0006-291X(05)80987-8&rft_id=info:pmid/1339271&rft.aulast=MacLaren&rft.aufirst=DC&rft.au=Kagan, RM&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
Ingrosso D, Kagan RM, Clarke S (1991). "Distinct C-terminal sequences of isozymes I and II of the human erythrocyte L-isoaspartyl/D-aspartyl protein methyltransferase". Biochem. Biophys. Res. Commun. 175 (1): 351–8. doi:10.1016/S0006-291X(05)81242-2. PMID1998518.351-8&rft.date=1991&rft_id=info:doi/10.1016/S0006-291X(05)81242-2&rft_id=info:pmid/1998518&rft.aulast=Ingrosso&rft.aufirst=D&rft.au=Kagan, RM&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
Gilbert JM, Fowler A, Bleibaum J, Clarke S (1988). "Purification of homologous protein carboxyl methyltransferase isozymes from human and bovine erythrocytes". Biochemistry. 27 (14): 5227–33. doi:10.1021/bi00414a042. PMID3167043.5227-33&rft.date=1988&rft_id=info:doi/10.1021/bi00414a042&rft_id=info:pmid/3167043&rft.aulast=Gilbert&rft.aufirst=JM&rft.au=Fowler, A&rft.au=Bleibaum, J&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
Ota IM, Gilbert JM, Clarke S (1988). "Two major isozymes of the protein D-aspartyl/L-isoaspartyl methyltransferase from human erythrocytes". Biochem. Biophys. Res. Commun. 151 (3): 1136–43. doi:10.1016/S0006-291X(88)80484-4. PMID3355545.1136-43&rft.date=1988&rft_id=info:doi/10.1016/S0006-291X(88)80484-4&rft_id=info:pmid/3355545&rft.aulast=Ota&rft.aufirst=IM&rft.au=Gilbert, JM&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
Tsai W, Clarke S (1994). "Amino acid polymorphisms of the human L-isoaspartyl/D-aspartyl methyltransferase involved in protein repair". Biochem. Biophys. Res. Commun. 203 (1): 491–7. doi:10.1006/bbrc.1994.2209. PMID8074695.491-7&rft.date=1994&rft_id=info:doi/10.1006/bbrc.1994.2209&rft_id=info:pmid/8074695&rft.aulast=Tsai&rft.aufirst=W&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
DeVry CG, Tsai W, Clarke S (1997). "Structure of the human gene encoding the protein repair L-isoaspartyl (D-aspartyl) O-methyltransferase". Arch. Biochem. Biophys. 335 (2): 321–32. CiteSeerX10.1.1.630.8527. doi:10.1006/abbi.1996.0513. PMID8914929.321-32&rft.date=1997&rft_id=https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.630.8527#id-name=CiteSeerX&rft_id=info:pmid/8914929&rft_id=info:doi/10.1006/abbi.1996.0513&rft.aulast=DeVry&rft.aufirst=CG&rft.au=Tsai, W&rft.au=Clarke, S&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
Enünlü I, Pápai G, Cserpán I, et al. (2003). "Different isoforms of PRIP-interacting protein with methyltransferase domain/trimethylguanosine synthase localizes to the cytoplasm and nucleus". Biochem. Biophys. Res. Commun. 309 (1): 44–51. doi:10.1016/S0006-291X(03)01514-6. PMID12943661.44-51&rft.date=2003&rft_id=info:doi/10.1016/S0006-291X(03)01514-6&rft_id=info:pmid/12943661&rft.aulast=Enünlü&rft.aufirst=I&rft.au=Pápai, G&rft.au=Cserpán, I&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">
Lanthier J, Desrosiers RR (2007). "Regulation of protein L-isoaspartyl methyltransferase by cell-matrix interactions: involvement of integrin alphavbeta3, PI 3-kinase, and the proteasome". Biochem. Cell Biol. 84 (5): 684–94. doi:10.1139/o06-055. PMID17167531.684-94&rft.date=2007&rft_id=info:doi/10.1139/o06-055&rft_id=info:pmid/17167531&rft.aulast=Lanthier&rft.aufirst=J&rft.au=Desrosiers, RR&rfr_id=info:sid/en.wikipedia.org:PCMT1" class="Z3988">