Non-genomic effect of estradiol on plasma membrane calcium pump activity in vitro.

The aim of the presented study was to compare the effect of 17-beta-estradiol on the hydrolytic activity of plasma membrane calcium pump (PMCA) purified from excitable (rat cortical synaptosomes) and non-excitable (human erythrocytes) cells. Both types of cell membranes contained different composition of the PMCA isoforms. To elucidate if the hormone action could depend on structure of PMCA protein, we assayed the hormone effect on Ca(2+)-ATP-ases pretreated for 15 and 40 min with trypsin.

The isoform- and location-dependence of the functioning of the plasma membrane calcium pump.

The plasma membrane is a specialised multi-component structure with inter- and intracellular signalling functions. Ca2+ plays a crucial role in cellular physiology, and an ATP-driven plasma membrane calcium pump (PMCA) plays the greatest role in the maintenance of a low free Ca2+ concentration in the cytoplasm. The enzyme is coded by four separate genes (PMCA 1-4), and, due to alternative splicing, more than 20 variants can exist.