Comparison of the Isoelectric and Molecular Weight Properties of Tubulin Subunits

Brain tubulin subunits were separated by a combination of isoelectric focusing and electrophoresis in the presence of sodium dodecyl sulfate (SDS) using a two‐dimensional polyacrylamide slab gel technique. Isoelectric focusing separated tubulin subunits into two major groups of bands, such that the more acidic group corresponded to the α subunit and the less acidic group corresponded to the β subunit. In addition, isoelectric focusing resolved the β subunit into two subspecies which differed slightly in isoelectric properties but were the same apparent molecular weight. The a subunit was resolved into many subspecies that appear to differ from each other by both apparent molecular weight and isoelectric properties.