Lysosomal accumulation of the hormone-receptor complex during receptor- mediated endocytosis of human choriogonadotropin

The experiments presented herein were designed to determine the fate of the human choriogonadotropin (hCG) receptor during endocytosis of the receptor-bound hCG. Using several biochemical approaches, it is shown that the receptor is internalized together with the hormone into endocytic vesicles and transferred to lysosomes without ligand dissociation. Once delivered to the lysosomes, the hCG-receptor complex dissociates, and the free hormone is degraded. This pathway appears to prevent receptor recycling and probably promotes receptor degradation.