Electrofocusing of human myocardial nuclear proteins yielded five peak
s of DNA methylase activity in the pH range 3.5-8.2. One peak was reso
lved by two-dimensional electrophoresis into six components of 10, 25,
35, 43, 67; and 120K; the 43K species corresponded in mobility to act
ins. This fraction exhibited DNA(cytosine) methyltransferase activity.
Sequence comparison between human actins and bacterial DNA methylases
revealed extended regions of homology in their C-terminal parts.