Alteration of binding properties and cytoskeletal attachment of nerve growth factor receptors in PC12 cells by wheat germ agglutinin

Abstract

Incubation of PC12 cells preloaded with 1251-nerve growth factor (NGF) reveals rapidly and slowly dissociating binding components indicative of a heterogeneous population of receptors. If the cells are previously exposed to wheat germ agglutinin (WGA) for 30 min, NGF now binds to an apparently homogeneous receptor population which exhibit slow dissociation kinetics. Total binding is also reduced by 50%. If WGA is added subsequent to 12≈I-NGF, total binding is not diminished, but rapidly dissociating receptors occupied with NGF are all converted to the slowly dissociating form. This conversion of receptors occurs rapidly, reaching completion within 2 rain at 37 ° or 4°C, and is unaffected by metabolic energy poisons, suggesting that WGA-induced slowly dissociating receptors are not the product of internalization. The effects of the lectin are blocked by the sugar N-acetyI-D-glucosamine, and the lectin-induced slowly dissociating receptors are converted back to rapidly dissociating receptors by addition of this same sugar. WGA also affects the association of the NGF receptor with the Triton X-100 cytoskeleton. >90% of bound ≈2≈I-NGF becomes associated with Triton X-100 insoluble cytoskeletons in the presence of the lectin, compared with <20% before lectin addition. Cytoskeleton association of the NGF receptor by WGA shows similar kinetics as the conversion of rapidly to slowly dissociating receptors. This interaction may be involved in the alteration of NGF-receptor binding properties produced by this lectin. © 1982, Rockefeller University Press., All rights reserved.