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 NPYY2 receptor

Guinea-pig neuropeptide Y-1 and rat pancreatic polypeptide Y-4 receptors ex pressed in Chinese hamster ovary cells were internalized rapidly upon attac hment of selective peptide agonists. The Y-1 and Y-2, but not the Y-4, rece ptor also internalized the nonselective neuropeptide Y receptor agonist, hu man/rat neuropeptide Y. The internalization of guinea-pig neuropeptide Y-2 receptor expressed in Chinese hamster ovary cells was small at 37 degreesC, and essentially absent at or below 15 degreesC, possibly in connection to the large molecular size of the receptor-ligand complexes (up to 400 kDa fo r the internalized fraction). The rate of intake was strongly temperature d ependent, with essentially no internalization at 6 degreesC for any recepto r. 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 block ed, and that of the Y-2 receptor significantly inhibited, by phenylarsine o xide, 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 mone nsin. Thus, in Chinese hamster ovary cells the Y-1 and Y-4 receptors have m uch larger subcellular dynamics than the Y-2 receptor. This differential co uld also hold in organismic systems, and is comparable with the known diffe rences in internalization of angiotensin, bradykinin, somatostatin and opio id receptor subtypes.