Self-interaction of dynein from Tetrahymena cilia

The molecular mass (Mr) and enzymic activity of the larger dynein species from Tetrahymena thermophila has been studied in the high (600 mM) to low (40 mM) ionic strength range. The apparent Mr is found to vary with both ionic strength (by sedimentation velocity and quasi elastic light scattering analysis) and with protein concentration at low ionic strength (by sedimentation equilibrium analysis). These data indicate a strong self-interaction, resulting in dimer formation under low salt conditions. There is no evidence for the formation of species of higher than dimeric mass. A molecular mass for the dynein monomer of 1.64 x 10(6) daltons has been determined, a value rather lower than previous published estimates. The ATPase activity of dynein increases with increasing ionic strength. The possible relationship between this effect and the self-association phenomenon is discussed.