Separation and Proteolytic Mapping of the Two [³H] Cytochalasin B Photoaffinity Labeled D-Glucose-Sensitive Proteins in the Chicken Embryo Fibroblast Plasma Membrane

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Photoaffinity labeling with [³H] cytochalasin B detects two D-glucose-sensitive proteins in the chicken embryo fibroblast (CEF) plasma membrane, which accumulate under conditions of glucose starvation and are probably involved in the glucose transport system (Pessin, J. E., et al. (1982) Proc. Natl. Acad. Sci. U. S. 79, 2286-2290). The two labeled components, designated as peak I (Mr 45, 000) and II (Mr 52, 000) com-ponents, were separated by preparative gel electrophoresis in the presence of sodium dodecyl sulfate. The fractions were digested with S. aureus V8 or papain, and the radioactive products were analyzed by one-dimensional gel electrophoresis. The peptide maps showed that they have different peptide structures. Peptide maps of authentic actin, a possible contaminant of the peak I fractions, were quite different from those of the peak I component. Rous sarcoma virus-transformed CEF have two components similar as to apparent molecular size and peptide maps to those present in glucose-starved cells. The peak I and II components show minimal affinity to agarose-bound Ricinus communis agglutinin which binds the human erythrocyte glucose transporter quite well. The peak II component was more susceptible to proteolysis than the peak I one or the human erythrocyte glucose transporter. However, the peptide maps of the peak II component were similar to those of the human erythrocyte glucose transporter.