The overall objective is to gain an understanding of how protein-protein and protein-lipid interactions create functionally important structures in biological membranes. To investigate protein-lipid interaction, we shall study by direct means the binding of both lipids and lipid analogs to several purified membrane proteins. As one example of protein-protein interaction, we shall study the association between erythrocyte membrane proteins that are thought to be components of a framework that may determine the size, shape and deformability of the cell envelope. Both protein-protein and protein-lipid interactions may be important in the creation of channels or pores that carry ions across membranes from one side to the other. We shall study the Ca ion Activated ATPase from sarcoplasmic reticulum and the presumed anion transport protein of the erythrocyte as examples.