Fractionation of membrane vesicles, membrane-lipid hybrid vesicles and detergent-solubilized membrane will be continued to identify associations and interactions between membrane proteins. Fractionation and reconstitution of Triton X-100-solubilized membrane will be continued aimed at isolation of components of the Ca2 ion transport system. High resolution electrophoretic analysis of detergent-solubilized membrane will be continued aimed at associating functional properties with individual proteins. Studies will be continued of factors modulating Ca2 ion transport activity of membrane vesicles.