Microtubules are constituent parts of the mitotic apparatus, cilia, flagella, and elements of the cytoskeleton. They consist principally of 2 soluble proteins, alpha- and beta-tubulin, each of about 55,000 kDa.
Antibodies against beta Tubulin are useful as loading controls for Western Blotting. However it should be noted that levels of beta Tubulin may not be stable in certain cells. For example, expression of tubulin in adipose tissue is very low (Spiegelman and Farmer, Cell, 1982, 29(1):53-60) and therefore beta Tubulin should not be used as loading control for these tissues.