Lectin-induced rearrangement of an immature hematopoietic cell surface marker

Experiments were carried out to examine the possible physiological role of disordered membrane domains in hematopoietic cell surface differentiation. The hematopoietic stem cell line 416B has been shown to bind the dye merocyanine 540 (MC540), a fluorescent probe which may be specific for disordered regions of lipid bilayers (Williamson et al., 1981). The surface receptors for the lectins Concanavalin A (Con A) and wheat germ agglutinin (WGA) exhibit patchy distributions on the surface of 416B cells which correspond to the distribution of MC540 binding regions. Appropriate incubation of these cells with either of the two lectins results in the induced formation of a cap. The binding regions for MC540 and the receptors for the other lectin become localized to the same region of the membrane by this process. Such coordinated rearrangements of surface glycoproteins associated with disordered lipid domains may play a role in the cocapping of disparate surface molecules (Raz and Bucana, 1980) or in differentiation-related cell surface rearrangements (Schlegel et al., 1980).