On the apparent homology of actin and tubulin

Muscle actin and ciliary A-tubulin from Pecten irradians have molecular weights of 46,000 and 59,000, respectively, as measured by sodium lauryl sulfate-polyacrylamide-gel electrophoresis. Tryptic and chymotryptic peptides obtained from these proteins are very dissimilar, indicating that there is little significant homology.