The p36 substrate of tyrosine-specific protein kinases co-localizes with non-erythrocyte alpha-spectrin antigen, p230, in surface lamina of cultured fibroblasts.

Biochemical and immunofluorescence studies have demonstrated that p36, a major substrate for the tyrosine-specific protein kinases induced by several sarcoma viruses and epidermal growth factor, is associated with plasma membranes and detergent-resistant cytoskeletal structures of cultured cells. We have used here polyclonal antisera and monoclonal antibodies in indirect immunofluorescence microscopy to study the subcellular location of p36 and the p230, which is a subplasmalemmal polypeptide showing immunologic cross-reactivity with erythrocyte alpha-spectrin. Both p36 and p230 showed a diffuse distribution in fixed and permeabilized cells and were localized in a surface lamina-like network in Triton-extracted cells. In double-staining experiments, an extensive co-distribution between these proteins was seen in detergent-treated cultured fibroblasts. These results, together with our previous work, suggest that the p36 protein is an integral part of the detergent-resistant proteinaceous network at the cytoplasmic face of the plasma membrane.