ANALYTICAL SEDIMENTATION STUDIES OF TURKEY GIZZARD MYOSIN LIGHT CHAIN KINASE AND TELOKIN

Sedimentation equilibrium and velocity studies were performed with turkey gizzard myosin light chain kinase (MLCK) and telokin, a small protein apparently corresponding to the sequence of the COOH-terminal end of MLCK. The measurements carried out with MLCK give values for the monomer molecular weight (M(r)), sedimentation coefficient (s20-degrees,w), and virial coefficient (A2) of 108,000, 3.74 S, and -1.95 x 10(-4) mol. ml . g-2, respectively, In the case of telokin, M(r) = 18,500; s20-degrees,w = 1.63 S; and A2 = 5.81 x 10(-4) mol . ml . g-2. Combination of the results of the two kinds of experiment shows that MLCK is a rod-shaped molecule (a/b = 18.9) with a Stoke's radius of 69 angstrom. Telokin is also elongated (alb = 8.3) with a Stoke's radius of 29 angstrom. MLCK apparently exhibits self-association, with 15% of the protein sedimenting as a dimer in the experiments.