Binding of plasma membrane glycoproteins to the cytoskeleton during patching and capping is consistent with an entropy-enhancement model.
Concentrations of concanavalin A that induced patching and capping of cell surface receptors on Dictyostelium discoideum also induce binding of the receptors to the cortical cytoskeleton, which was isolated by density-gradient centrifugation. The receptors were solubilized by deoxycholate, purified by affinity chromatography, and used to determine whether the receptors bound directly to the cytoskeletal protein, actin. As the concentration of actin was increased, many of the receptors became bound to purified filamentous rabbit muscle actin, even in the absence of concanavalin A. As in the ligation-induced binding of receptors to the cortical cytoskeleton in cells, concanavalin A induced much stronger binding of the purified receptors to filamentous actin. The results were consistent with a previously stated hypothesis that induction of receptor binding to the cytoskeleton during their patching and capping is driven by clustering the receptors, which reduces their translational entropy and by doing so enhances their avidity for the cytoskeleton.
Shiozawa
J A
JA
Department of Biochemistry, University of Massachusetts, Amherst 01003.
Brandts
J F
JF
Jacobson
B S
BS
D000199:Actins / Q000378:metabolism; D000818:Animals; D002846:Chromatography, Affinity; D003599:Cytoskeleton / Q000378:metabolism*; D004023:Dictyostelium / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins; D011817:Rabbits; D011940:Receptor Aggregation; D011952:Receptors, Concanavalin A / Q000302:isolation & purification; D011971:Receptors, Immunologic / Q000302:isolation & purification* / Q000378:metabolism; D013816:Thermodynamics
D000199:Actins; D008562:Membrane Glycoproteins; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins; D011952:Receptors, Concanavalin A; D011971:Receptors, Immunologic; C032193:glycoprotein receptor GPIb-IX