Cloned neuropeptide Y (NPY) Y 1 and pancreatic polypeptide Y 4 receptors expressed in Chinese hamster ovary cells show considerable agonist‐driven internalization, in contrast to the NPY Y 2 receptor

Guinea‐pig neuropeptide Y 1 and rat pancreatic polypeptide Y 4 receptors expressed in Chinese hamster ovary cells were internalized rapidly upon attachment of selective peptide agonists. The Y 1 and Y 2 , but not the Y 4 , receptor also internalized the nonselective neuropeptide Y receptor agonist, human/rat neuropeptide Y. The internalization of guinea‐pig neuropeptide Y 2 receptor expressed in Chinese hamster ovary cells was small at 37 °C, and essentially absent at or below 15 °C, possibly in connection to the large molecular size of the receptor−ligand complexes (up to 400 kDa for the internalized fraction). The rate of intake was strongly temperature dependent, with essentially no internalization at 6 °C for any receptor. Internalized receptors were largely associated with light, endosome‐like particulates. Sucrose dose‐dependently decreased the internalization rate for all receptors, while affecting ligand attachment to cell membrane sites much less. Internalization of the Y 1 and the Y 4 receptors could be blocked, and that of the Y 2 receptor significantly inhibited, by phenylarsine oxide, which also unmasked spare cell‐surface receptors especially abundant for the Y 2 subtype. The restoration of Y 1 and Y 4 receptors after agonist peptide pretreatment was decreased significantly by cycloheximide and monensin. Thus, in Chinese hamster ovary cells the Y 1 and Y 4 receptors have much larger subcellular dynamics than the Y 2 receptor. This differential could also hold in organismic systems, and is comparable with the known differences in internalization of angiotensin, bradykinin, somatostatin and opioid receptor subtypes.