The tubulins of animals, plants, fungi and protists implications for metazoan evolution.

alpha-Tubulin subunits from trout (S. gairdneri) sperm tails, sea urchin (S. purpuratus) cilia, protistan alga (C. elongatum ) flagella and rose (Paul's Scarlet) cytoplasm have been characterized by limited proteolytic cleavage with the enzyme Staphylococcus aureus protease and electrophoresis of the digestion products on SDS-PAGE. The resulting patterns corresponded to either of two major types representative of animal and non-animal alpha-tubulins, respectively. A total of 28 alpha-tubulins have now been characterized by this method. They are classified in this paper according to the type of cleavage pattern generated by the enzyme S. aureus protease. The implications of these results for metazoan evolution are discussed.