Jf. Glickman et al., PEPTIDE-MAPPING OF THE MURINE DNA METHYLTRANSFERASE REVEALS A MAJOR PHOSPHORYLATION SITE AND THE START OF TRANSLATION, The Journal of biological chemistry, 272(28), 1997, pp. 17851-17857
The murine DNA methyltransferase catalyzes the transfer of methyl grou
ps from S-adenosylmethionine to cytosines within d(CpG) dinucleotides.
The enzyme is necessary for normal embryonic development and is impli
cated in a number of important processes, including the control of gen
e expression and cancer, Metabolic labeling and high pressure liquid c
hromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS)
were performed on DNA methyltransferase purified from murine erythrole
ukemia cells, Serine 514 was identified as a major phosphorylation sit
e that lies in a domain required for targeting of the enzyme to the re
plication foci, These results present a potential mechanism for the re
gulation of DNA methylation. HPLC-ESI-MS peptide mapping data demonstr
ated that the purified murine DNA methyltransferase protein contains t
he N-terminal regions predicted by the recently revised 5' gene sequen
ces (Yoder, J. A., Yen, R.-W. C., Vertino, P. M., Bestor, T. H., and B
aylin, S. B. (1996) J. Biol, Chem, 271, 31092-31097), The evidence sug
gests a start of translation at the first predicted methionine, with n
o alternate translational start sites, Our peptide mapping results pro
vide a more detailed structural characterization of the DNA methyltran
sferase that will facilitate future structure/function studies.