PURIFICATION AND STABILIZATION OF MOUSE DNA METHYLTRANSFERASE

Cytosine methylation within DNA has been implicated in genetic imprint ing, X-chromosome inactivation, regulation of tissue-specific gene exp ression, aging, and cancer. Unfortunately, DNA (cytosine-5)-methyltran sfersases (EC 2.1.1.37) from various mammalian sources have been diffi cult to isolate and stabilize, precluding investigations of these crit ical enzymes. We describe a novel FPLC purification of the 190,000 Mr DNA methyltransferase from mouse Friend erythroleukemia cells. The hom ogeneous 190 kD Mr form of the enzyme is the only polypeptide detected at various stages of cell growth and has not undergone detectable N-t erminal proteolysis. (C) 1995 Academic Press, Inc.