Photoaffinity labeling of plasma membrane receptors for cytochalasins in Ehrlich tumor cells.

Treatment of purified Ehrlich ascites cell plasma membranes either with [3H]cytochalasin B or [3H]19-O-acetylchaetoglobosin A under photolytic conditions produced several radioactive polypeptides which were characterized by SDS-PAGE analyses. The major proteins so photolabeled were in the 60,000-80,000 Da range, with less labeling found in polypeptides smaller than 43,000 and greater than 90,000 Da. Immunofluorescent staining failed to identify the major photolabeled component as actin. It is concluded, in keeping with prior investigations using other cell types, that the predominant proteins photolabeled by cytochalasins are affiliated with the glucose-transport system.