Antigenicity of brain microtubule protein

Abstract Antisera were produced against bovine and mouse brain microtubular protein (tubulin) preparations. DEAE batch-prepared and vinblastine-precipitated tubulin appear to be highly similar immunogens by microcomplement fixation. When tubulin is removed from the soluble fraction of mouse brain homogenates with vinblastine, C′ fixation of this fraction falls 80% and the colchicine binding decreases 95%, indicating the correspondence between antigenicity and the amount of tubulin present. The antisera to bovine brain tubulin cross-react with tubulin from mouse, chicken and turtle brain. On the other hand, the antisera do not cross-react appreciably with vinblastine precipitates from spleen, liver, or pancreas owing to the small amount of tubulin relative to other proteins present in the vinblastine precipitates from soluble fractions of these organs. It is suggested that tubulin is an evolutionary conservative protein and the availability of antisera should be valuable in studies on microtubules.