Membrane-associated tubulin in the rat anterior pituitary and GH₃ cells

Plasma membranes from anterior pituitary lobes of rats and GH³ cells were exposed to monoclonal anti-β tubulin antibodies or normal mouse IgG, and treated with FITC-labeled anti-mouse IgG. Specimens were visualized with a microscope equipped with epifluorescence optics. Tubulin-specific fluorescence was very prominent in membranes incubated with tubulin antibody and was negligible in membranes incubated with normal mouse IgG or FITC-labeled anti-mouse IgG alone. Two dimensional electrophoresis revealed that 27% of the rat pituitary tubulin is β-tubulin and 73 % is β-tubulin; 17% of the GH₃ cell tubulin is β-tubulin and 83% is α-tubulin. These results suggest that tubulin is a component of plasma membranes of the rat pituitary and GH³ cells.