Binding of paratropomyosin to beta-connectin from chicken skeletal muscle.

We found that paratropomyosin bound to beta-connectin, in examining binding of paratropomyosin at the junction of A- and I-bands of sarcomeres. The turbidity of a mixture of beta-connectin and paratropomyosin was greater with more paratropomyosin added, but high concentrations of Ca2+ suppress this increase. These results suggest that paratropomyosin is released from connectin filaments at the A-I junction region by increased concentrations of calcium ions in postmortem skeletal muscles.