nmdcat.online
BIO NMDCAT Muscles
nmdcat.online July 28, 2026

The characteristic feature of the calcium-binding protein in smooth muscle is that, unlike the calcium-binding protein in skeletal muscle, it:

A. Is permanently attached to the actin filament
B. Directly activates an enzyme that phosphorylates myosin
✓
C. Inhibits the binding of myosin to actin until calcium is removed
D. Is located entirely within the sarcoplasmic reticulum

📝 Explanation

In skeletal muscle, calcium binds to troponin on the actin filament to expose binding sites. In smooth muscle, calcium binds to calmodulin in the cytosol, which then directly activates an enzyme (myosin light-chain kinase) that phosphorylates the myosin head to initiate contraction.

📖 Additional Information

  • Is permanently attached to the actin filament
  • Directly activates an enzyme that phosphorylates myosin
  • Inhibits the binding of myosin to actin until calcium is removed
  • Is located entirely within the sarcoplasmic reticulum

In skeletal muscle, calcium binds to troponin on the actin filament to expose binding sites. In smooth muscle, calcium binds to calmodulin in the cytosol, which then directly activates an enzyme (myosin light-chain kinase) that phosphorylates the myosin head to initiate contraction.

🔗 Share This Question

Facebook Twitter LinkedIn WhatsApp

🧭 Navigate Questions

Previous Question

An increase in physical training induces hypertrophy in skeletal muscle. The biological mechanism behind this increase in muscle size is primarily:

Next Question

Concerning the duration of muscle twitches, if a skeletal muscle twitch lasts approximately 10-100 milliseconds, what is the expected duration of a typical smooth muscle contraction?

Back to All Questions

🔗 Related MCQs

Concerning the duration of muscle twitches, if a skeletal muscle twitch lasts approximately 10-100 milliseconds, what is the expected duration of a typical smooth muscle contraction?
July 28, 2026
The physiological response to hypoxia (low oxygen) differs among muscle types. Which muscle type is most susceptible to irreversible damage following a brief period of hypoxia?
July 28, 2026
A medical relevance of understanding muscle tissue differences is the development of calcium channel blockers. These drugs are primarily used to treat hypertension (high blood pressure) and angina. They exert their biological effect mainly by acting on:
July 28, 2026
During the process of cell differentiation, which muscle type loses its ability to divide and form new cells almost completely, relying solely on hypertrophy for growth?
July 28, 2026
The functional relationship between the shape of a muscle cell and its tissue type is evident when observing spindle-shaped cells. This specific morphology allows the cells to:
July 28, 2026

Categories

View all →