Use the following information to answer Questions 3 and 4. You do not need to know more about parathyroid hormone or pseudohypoparathyroidism than the information given. Pseudohypoparathyroidism is a heritable disorder caused by target-organ unresponsiveness to parathyroid hormone (a polypeptide hormone secreted by the parathyroid gland). One of the mutations that causes this disease occurs in the gene encoding G α s in certain cells. 3. The receptor for parathyroid hormone is most likely which one of the following?