Interaction of polyadenylic acid (5′) with histone H1 or protamine

The interaction between polyadenylic acid (5′) (poly[A]) and histone (or protamine) was analyzed by electrophoretic retardation of poly[A]‐histone (or protamine) complex in agarose gel. The potency of interaction was protamine > histone H1, arginine‐rich histone > other histones. The catalytic subunit of cyclic AMP‐dependent protein kinase effectively decreased the electrophoretic retardation of poly[A]‐histone H1. The interaction between poly[A] and histone H1 was also detected by the drastically enhanced absorbance around 340 nm. The findings may implicate a regulatory role of histone H1 on mRNAs through its binding on poly[A] tails.