A map of photolytic and tryptic cleavage sites on the β heavy chain of dynein ATPase from sea urchin sperm flagella

Abstract

NH2-terminal analysis of the α and β heavy chain polypeptides (M(r) > 400,000) from the outer arm dynein of sea urchin sperm flagella, compared with that of the 230,000- and 200,000-M(r) peptides formed upon photocleavage of dynein by irradiation at 365 nm in the presence of vanadate and ATP, shows that the NH2 termini of the intact chains are acetylated and that the 230,000- and 200,000 M(r) peptides constitute the amino- and carboxy-terminal portions of the heavy chains, respectively. Tryptic digestion of the β heavy chain is known to separate it into two particles, termed fragments A and B, that sediment at 12S and 6S (Ow, R.A., W.-J.Y. Tang, G. Mocz, and I.R. Gibbons, 1987. J. Biol. Chem. 262:3409-3414). Immunoblots against monoclonal antibodies specific for epitopes on the β heavy chain, used in conjunction with photoaffinity labeling, show that the ATPase-containing fragment A is derived from the amino-terminal region of the β chain, with the two photolytic sites thought to be associated with the purine-binding and the γ-phosphate-binding areas of the ATP-binding site spanning an ~100,000 M(r) region near the middle of the intact β chain. Fragment B is derived from the complementary carboxy-terminal region of the β chain.