Recycling of the hepatocyte asialoglycoprotein receptor does not require delivery of ligand to lysosomes.

The hepatocyte asialoglycoprotein receptor is able to mediate the internalization of ligand in buffer devoid of Na+ but containing 0.15 M K+. Under these conditions, degradation of internalized ligand does not occur due to an inability to deliver the ligand to lysosomes. Instead, the ligand becomes localized in a vesicle with the same density as plasma membrane on Percoll gradients. This vesicle may be the functional equivalent of the uncoated vesicles observed by electron microscopy. Internalization of more than 20 glycoprotein molecules/high affinity surface receptor was observed under these conditions, indicating that delivery of ligand to lysosomes is not necessary for receptor reutilization.