Chromatographic separation of four Ser/Thr-protein phosphatases from solubilized ciliary membranes of Paramecium tetraurelia by heparin-Sepharose

Chromatography of deoxycholate-solubilized proteins from Paramecium ciliary membranes on heparin-Sepharose resolved three peaks of protein phosphatase activities: one type 2A-like and a type 2C phosphatase in the flow-through fractions, another type 2A-like enzyme in the 0.1 M NaCl eluate and type 1 protein phosphatase in the 0.5 M NaCl eluate. The differential sensitivity of the two type 2A-like phosphatases to heparin and protamine further substantiated the existence of distinct isozymes. Once solubilized, none of these ciliary phosphatases required detergent to remain soluble. The molecular mass as determined by chromatography on Superose 6 was in the range 30 000-45 000 dalton for all four protein phosphatases.