PHYSIOLOGY
MUSCLE CONTRACTION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
Which ion, when present, causes a change in conformation of tropomyosin?
|
|
Calcium
|
|
|
Sodium
|
|
|
Potassium
|
|
|
Lithium
|
Explanation:
Detailed explanation-1: -calcium ions bind to troponin, causing conformational changes in troponin that allow tropomyosin to move away from the myosin-binding sites on actin.
Detailed explanation-2: -Troponin binds to tropomyosin and helps to position it on the actin molecule; it also binds calcium ions.
Detailed explanation-3: -Troponin is shown in red (subunits not distinguished). Upon binding calcium, troponin moves tropomyosin away from the myosin-binding sites on actin (bottom), effectively unblocking it.
There is 1 question to complete.