Which of the Following is a Double-Stranded Protein That Blocks

Question

Which of the following is a double-stranded protein that blocks actin-binding sites?
A) myosin
B) DNA
C) tropomyosin
D) troponin

Accepted Answer

Tropomyosin is a double-stranded protein that blocks actin-binding sites in muscle cells, preventing myosin from binding and initiating muscle contraction. Myosin (A) is a motor protein that interacts with actin to generate force in muscle cells. DNA (B) is a hereditary material that contains genetic information, but it does not play a role in muscle contraction. Troponin (D) is a complex of three proteins that regulates tropomyosin's position on actin filaments in response to calcium ions, allowing myosin to bind and initiate muscle contraction. However, it is not itself a double-stranded protein that blocks actin-binding sites.