Response of isolated nuclei to phospholipid vesicles: a two dimensional gel electrophoresis analysis of H2SO4 soluble nuclear proteins after treatment with phosphatidylserine

Abstract H 2 SO 4 soluble proteins extracted from nuclei incubated with phosphatidylserine multilamellar vesicles (PS MLV) have been analysed by means of two-dimensional gel electrophoresis with particular attention to the uH2A fraction. A reduction of H1, H1∘ and proteins A5, B7, B15 and B23 has been observed in lipid treated nuclei, while the core histones, as well as uH2A are unaffected by liposome treatment. Since these proteins show in vitro the same binding affinity for PS, their behaviour appears to be related to difference in localization in the nucleosome, responsible for their variable accessibility in the chromatin. These results might explain how this phospholipid induces a decondensation of chromatin and a stimulation of RNA synthesis.