Question

The receptor for aldosterone appears to have evolved much earlier than aldosterone itself. Propose a hypothesis to explain how this might have occurred.

Answer 1

The receptor for aldosterone probably evolved before aldosterone because it binded with other structurally similar ligands and hormones. On another note aldosterone is a member of the mineralocorticoid family, so there are a number of other steroid hormones similar in chemical structural to aldosterone itself that contribute towards maintaining homeostasis or stimulating other physiological actions.

Thus the receptor evolved in order to bind with more ancient or preceding ligands related to aldosterone that served some vital functions in the human endocrine system.