| 背景信息 |
Melanocortin 2 receptor accessory protein (MRAP) is a small, single-pass transmembrane protein that forms antiparallel homodimers with unique dual topology. It is essential for the trafficking and functional maturation of the melanocortin 2 receptor (MC2R), also known as the ACTH receptor. MRAP facilitates the exit of MC2R from the endoplasmic reticulum, ensures its correct glycosylation, and enables its signaling at the plasma membrane. While primarily required for MC2R, MRAP also modulates the ligand sensitivity of other melanocortin receptors (MC1R, MC3R, MC4R, and MC5R). Clinically, biallelic loss-of-function mutations in MRAP lead to familial glucocorticoid deficiency type 2. This condition is characterized by severe cortisol deficiency and ACTH resistance, often presenting in infancy with life-threatening hypoglycemia and adrenal crises. |