The objectives of the proposed research are: 1. To characterize further the protein that associates firmly with the cytoplasmic surface of the normal red cell membrane during sterile incubation in vitro. a. To determine if the globin that comprises at least part of this bound protein includes alpha and beta chains and in what proportion. b. To identify and quantify other protein(s) bound. 2. To identify the membrane polypeptide(s) to which globin chains bind during incubation of normal red cells. 3. To determine changes in the topography of the external surface of the normal red cell during incubation and ATP depletion using the impermeant radioactive probe (125I)diazodiiodosulfanilic acid (125I)DDISA). 4. To ascertain what proteins are lost from the normal red cell during incubation (membrane fragments and/or external proteins). 5. To extend the above studies of both internal and external red cell membrane surfaces to abnormal red cells, in particular cells from splenectomized normal individuals and cells from splenectomized and unsplenectomized patients with hereditary spherocytosis. 6. To quantify total and individual membrane proteins of red cells stored under usual Blood Bank conditions and to investigate surface topography of stored cells using (125I)DDISA.