Imagine that a researcher has dissected out a single muscle bundle from a triceps muscle biopsy. She sections this bundle and stains it for a variety of muscle-associated proteins. After this staining, when she zooms in on a sarcomere, she notices that a certain protein always dots the periphery along the length of the thin filaments. This protein is MOST likely:

Question

Quizplus · Accepted Answer

Tropomyosin is a protein that winds around the actin filament in the sarcomere, covering the myosin binding sites on actin. It is located along the length of the thin filaments, so it would appear as a dot along the periphery of each sarcomere. Actin and myosin are also present in the sarcomere, but they would not appear as dots along the periphery. Titin is a large elastic protein that spans from the Z-disc to the M-line and is not located along the thin filaments. Z protein is a protein found at the Z-disc region within the sarcomere, which is not present along the length of the thin filaments.

Imagine That a Researcher Has Dissected Out a Single Muscle