Which of the Following Is (Are)characteristic of the (Na⁺-K⁺)-ATPase

question 19

Multiple Choice

Which of the following is (are) characteristic of the (Na⁺-K⁺) -ATPase?
(I) It binds Na⁺ and K⁺ simultaneously prior to binding ATP
(II) It is covalently modified by phosphorylation at an Asp residue when Na⁺ is present.
(III) Transport of Na⁺ and K⁺ occur in a 1:1 ratio,thus maintaining a balanced gradient until opening of the gated portion of the channel.
(IV) It is essential for excitation of nerve cells.

• A)I,II,IV
• B)II,III,IV
• C)II,IV
• D)II,III
• E)II

---

Definitions:

Gigantism

A condition characterized by excessive growth and height significantly above average, due to an overproduction of growth hormone in childhood.

Antidiuretic Hormone

A hormone released by the pituitary gland that regulates water balance by reducing urine production and increasing water reabsorption by the kidneys.

Posterior Pituitary

The rear portion of the pituitary gland, responsible for the storage and release of antidiuretic hormone (ADH) and oxytocin, which play roles in water balance and childbirth respectively.

Anterior Pituitary

A glandular portion of the pituitary gland responsible for the release of several key hormones influencing various body functions.