Turkey Gizzard Caldesmon Molecular Weight and Shape

The molecular weight of chicken gizzard muscle caldesmon has been measured previously by sedimentation equilibrium in the analytical ultracentrifuge and found to be 93 ± 4 kDa [P. Graceffa, C.-L. A. Wang, and W. F. Stafford (1988) J. Biol. Chem. 263, 14196-14202]. The molecular weight of turkey gizzard caldesmon has been determined by another group to be 75 ± 2 kDa by the same technique [D. A. Malecik, J. Ausio, C. E. Byles, B. Modrell, and S. R. Anderson (1989) Biochemistry 28, 8227-8233]. We have reevaluated the molecular weight of the turkey protein by sedimentation equilibrium analysis and found a value of 90 ± 3 kDa, indicating that turkey gizzard caldesmon is a typical muscle caldesmon and does not belong to the class of smaller nonmuscle caldesmons. The two muscle caldesmons do not comigrate during polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, indicating that they have different amino acid sequences.