HISTONES AND BASIC POLYPEPTIDES ACTIVATE CA2(+) CATION INFLUX IN VARIOUS CELL-TYPES/

Histone H2A (1-10 mu g/ml) added to Ehrlich ascite cell suspensions pr omoted: (i) Ca2+ influx, but no apparent intracellular Ca2+ mobilizati on; (ii) plasma-membrane depolarization and Na+ influx in Ca2+-free me dium, which were recovered by Ca2+ readmission; (iii) influx of other cations such as Ba2+, Mn2+, choline(+) and N-methyl-D-glucamine(+), bu t not of propidium(+), ethidium bromide and Trypan Blue. H2A-induced C a2+ influx and cell depolarization were: (i) blocked by La3+ and Gd3+, but not by various inhibitors of receptor-activated Ca2+-influx pathw ays/channels; (ii) mimicked by various basic polypeptides, with M-r > 4000; (iii) prevented or reversed by polyanions such as polyglutamate or heparin; (iv) present in other cell types, such as Jurkat, PC12 and Friend erythroleukaemia cells, but virtually absent from rat hepatocy tes and thymocytes. We conclude that cationic proteins/ polypeptides, by interacting in a cell-specific manner with the cell surface, can ac tivate in those cells putative non-selective Ca2+ channels and membran e depolarization.