2000 Global Researcher Conference Proceeding

March 10 - 12, 2000

Conference: 2000 Global Researcher Conference
Title: V2 vasopressin receptor-arrestin interactions
Authors: Innamorati, Giulio; Bowen-Pidgeon, Donna; Sadeghi, Hamid; Birnbaumer, Mariel
Institutions: Vita Salute University School of Medicine, University of Isfahan, National Institute of Environmental Health Sciences, UCLA School of Medicine
BirnbaumerSimilar to other G protein coupled receptors, upon binding to AVP the V2 vasopressin receptor is phosphorylated and internalized. We previously demonstrated that the internalized receptor did not recycle to the cell surface after removal of the hormone from the medium, and that the intracellular retention was mediated by the full phosphorylation of the last amino acids of the carboxy terminus. The possible role of non-visual arrestins 2 and 3 in the traffic of the V2R was examined, receptor internalization was enhanced by arrestins but they did not interfere with trapping of the V2R inside of the cell. The phosphorylated carboxy terminus of the receptor was found to interact with arrestins, but in addition, arrestins increased internalization of a truncated form of the receptor lacking the carboxy terminus. The experiments revealed the presence of two domains in the V2R that respond to expression arrestin with a significant enhancement in internalization.

The vasopressin-2 receptor (V2R) is synthesized within the cell and moves to the cell membrane. Exposure of the cell to vasopressin promotes entry of the receptor, a process called internalization. Internalization is aided by a process called phosphorylation, which is a process that links phosphate groups to the tail end of the V2R (i.e. the carboxy terminus). Innamorati, et al., investigated the possible role the cellular substances called non-visual arrestins 2 and 3 had on V2R internalization. They found that the arrestins enhanced V2R internalization and did not interfere with the cell’s ability to keep V2R from once again returning to the cell surface.

The phosphorylated carboxy terminus interacted with the arrestins. However, the researchers found that if a V2R did not have a carboxy terminus, arrestins would still increase the internalization of the V2R. Thus, the research revealed that there are two different sections of the V2R that interact with arrestin to result in increased internalization.