Cholera toxin induced redistribution of sialoglycolipid receptor at the lymphocyte membrane

The interaction of polyvalent ligands, such as antibodies or lectins with cell surface structures of living lymphocytes or other cell types, often leads to a redistribution of plasma membrane constituents into clusters, patches and caps. The redistribution process is not fully understood but it is a metabolically dependent active process, possibly involving the activity of contractile microfilaments [l] and microtubules [2,6]. It appears likely that receptors of the membrane may partially be immobilized by cross linkages with the ligands [3]. As a consequence, the complexes formed become concentrated in the tail position of the cell, as the free membrane components flow forward as a part of the normal process of cell movement [4]. However, the inhibition of the Con A-induced cocapping of unrelated membrane receptors, e.g. by colchicine, points to an additional involvement of colchicine-sensitive micro structures. Following cap formation, the ligandreceptor complexes can be taken up by the cell through pinocytosis and/or be shed into the medium [S] . It is unclear which of those phenomena may perhaps be an important factor for possible triggering of the cell [4,6]. Ligand-induced redistribution has