An endogenous inhibitor of active transport enzyme systems

Effect of histone H1 on the cytosolic calcium levels in human breast cancer MCF 7 cells

“…In histone H1 treated MCF 7 cells in the absence of extra cellular a transient increase in cytosolic calcium suggests efflux of calcium from the endoplasmic reticulum calcium pool causing its depletion, consequent to the inhibition of calcium uptake into ER. The possible reason for the decreased uptake of calcium into the ER could have resulted from the inhibition of Ca 2+ ATPase by histone H1 (Schwartz and Laseter, 1964). An increase in cytosolic calcium has been implicated in signal transduction pathway that mediates apoptosis (Kaiser and Edelman, 1977;Caron-Leslie and Cidlowski, 1991;Dowd et al, 1991Dowd et al, , 1992McConkey et al, 1989).…”

INFLUENCES OF PROTAMINE ON THE Na+, K+-DEPENDENT ATPase AND ON THE ACTIVE TRANSPORT PROCESSES OF POTASSIUM AND OFL-DOPA INTO BRAIN SLICES

“…Several authors have described the influence of protarnine on the activity of ATPase in rnicrosomal preparations. Little effect was observed in the presence of n4g++, Na+, and M+ together, though protamine showed a stinllulatory effect in the absence of Na+ (8,9) and an inhibitory effect in the presence of Nig++ alone (10). However, it was reported that active transport of K+ seemed to be inhibited by protamine (11).…”