The specific objectives are 1) to further our understanding of the molecular mechanisms involved in the phenomena of patching, capping and endocytosis induced by ligand-surface receptor interactions; 2) to perform comparative biochemical studies between ligand-induced endocytotic vesicles and plasma membranes in order to test a "selective membrane protein turnover" hypothesis; 3) to obtain information on the regulatory processes involved in the biosynthesis and mobility of membrane proteins and viral-coded glycoproteins. In the first part of the project, a novel iodination procedures mediated by lactoperoxidase coupled to specific antibodies will be used to analyze the biochemical composition in "patches" and "caps" and to determine the possible involvement of a regulatory membrane protein(s) X in transmembrane control. In addition, a new membrane fractionation procedure will be used to isolate pure endocytotic vesicles. Analysis of the membrane polypeptide and lipid compositions and the nature of the lectin receptors will be made in order to determine the possible relationships between endocytotic vesicles and plasma membranes. Iodination of the surface proteins on isolated "inside out" endocytotic vesicles will also provide an excellent opportunity to analyze the biochemical nature of the cytoplasmic side of plasma membrane. In the second part of this project, immunocytochemical techniques on ultrathin frozen sections will be used to study at ultrastructural level (1) the control mechanisms of contractile proteins in regulating ligand-induced membrane mobility and turnover (2) the biosynthetic pathways of surface immunoglobulin and viral-coded glycoproteins in normal lymphoid, myeloma and lymphoma cell lines.