A nuclear protein associated with actively transcribed nucleosomes exhibits Zn2+-binding activity

AbstractThe presence of the zinc-finger motif in nuclear protein structure often confers specific DNA-binding capabilities and, consequently, may implicate such proteins as being involved in gene regulation. We measured the zinc-binding capacity of nuclear proteins by using a zinc (Zn2+) blotting technique. This assay revealed that some non-histone proteins are selectively associated with this metal ion. Of particular interest, a nuclear protein, B2 (Mr 68000; pI 7.3), associated with actively transcribed nucleosomes and possibly involved with premessenger splicing, exhibits Zn2+-binding activity. Moreover, this activity can be achieved with as little as 2 μg of nuclear protein and the zinc-binding capacity is, on average, 2 ions per molecule of the protein B2