When troponin binds calcium,
A) it allows tropomyosin to bind actin.
B) ion channels open, and sodium rushes into the muscle cells.
C) it changes conformation, twisting tropomyosin and exposing the actin-myosin binding site.
D) it changes conformation, exposing the ATP binding site and allowing the actin-myosin bond to break.
E) calmodulin binds to calcium and starts a cascade by activating myosin kinase.

Question

Quizplus · Accepted Answer

When troponin binds calcium, it changes conformation, twisting tropomyosin and exposing the actin-myosin binding site. This enables myosin to bind to actin and initiate muscle contraction. The other options are incorrect as they describe unrelated processes.

When Troponin Binds Calcium