Comparative structure and chemistry of tubulins from different eukaryotes

Electrophoretic and peptide mapping have been used to examine α- and β-tubulins from chordates, tunicates, echinoderms, mollusks, brachiopods, ferns, fungi, green algae and heliozoans. Cytoplasmic, ciliary, flagellar, and axopodial tubulins were examined. The results show that β-tubulin is more conserved than α-tubulin. The large differences seen between axonemal and cytoplasmic tubulins and the similarity of all axonemal tubulins examined indicate that the genes for these two tubulin classes diverged prior to the appearance of metazoa and metaphyta. Comparisons of α-tubulins appear useful for tracing phyletic relationships within kingdoms whereas comparisons of β-tubulins may be better for relating the kingdoms to each other.