Internalization, G protein—coupled receptors

Adie EJ, Kalinka S, Smith L, Francis MJ, Marenghi A, Cooper ME, Briggs M, Michael P, Milligan G, Game S (2002) A pH-sensitive fluor, CypHer 5, used to monitor agonist-induced G protein-coupled receptor internalization in live cells. BioTechniques 33 1152-1157... 

Ferguson S. S., Downey W. E. R., Colapietro A. M., Barak L. S., Menard L. and Caron M. G. (1996) Role of beta-arrestin in mediating agonist-promoted G protein-coupled receptor internalization. Science 271, 363-366. 

Rossi F, Charlton CA, Blau HM. Monitoring protein-protein interactions in intact eukaryotic cells by beta-galactosidase complementation. Proc. Natl. Acad. Sci. U.S.A. 1997 94 8405-8410. Wehrman TS, Casipit CL, Gewertz NM, Blau HM. Enzymatic detection of protein translocation. Nat. Methods 2005 2 521-527. Hammer MM, Wehrman TS, Blau HM. A novel enzyme complementation-based assay for monitoring G-protein-coupled receptor internalization. FASEB J. 2007 21 3827-3834. 

H. Tong, H. A. Rockman, W. J. Koch, C. Steenbergen and E. Murphy, G protein-coupled receptor internalization signaling is required for cardioprotection in ischemic preconditioning, Circ Res 94, 1133-1141,(2004). 

Arrestins act as adaptor proteins that bind to phos-phorylated G protein-coupled receptors (GPCR) and link the receptors to clathrin-coated pits. (3-Arrestins are essential in the internalization of many GPCRs. 

Chronic opiate treatment results in complex adaptations in opioid receptor signaling. Much has been learned from studies on mechanisms of tolerance to the analgesic effects of opiates. This is a major clinical problem, as it means that ever-escalating doses are required for the treatment of chronic pain. The classic view was that tolerance reflects a decrease in functional opioid receptors via desensitization and internalization. Desensitization occurs when receptors are uncoupled from G proteins as a result of phosphorylation by G-protein-coupled receptor... 

Mundell, S. J., Pula, G., Carswell, K., Roberts, P. J., and Kelly, E. (2003) Agonist-induced internalization of metabotropic glutamate receptor 1A structural determinants for protein kinase C- and G protein-coupled receptor kinase-mediated internalization../. Neurochem. 84,294-304. 

Tsuga, H., Kameyama, K., Haga, T., Honma, T., Lameh, J., and Sadee, W. (1998) Internalization and down-regulation of human muscarinic acetylcholine receptor m2 subtypes. Role of third intracellular m2 loop and G protein- coupled receptor kinase 2. J. Biol. Chem. 273, 5323-5330. 

Terrell, J., S. Shih, R. Dunn, and L. Kicke. A function for monoubiquitination in the internalization of a G protein-coupled receptor. Mol Cell. 1 193-202.1998. 

Terrell J, Shih S, Dunn R, Hicke L (1998) A function for monoubiquitination in the internalization of a G protein-coupled receptor. Mol Cell 1 193-202 Tomoda K, Kubota Y, Kato J (1999) Degradation of the cydin-dependent-kinase inhibitor p27 is instigated by Jabl. Nature 398 160-165 Toyoshima F, Moriguchi T, Wada A, Fukuda M, Nishida, E (1998) Nudear export of cydin Bl and its possible role in the DNA damage-induced G2 checkpoint. EMBO J 17 2728-2735... 

Grossfield, A., Pitman, M.C., Feller, S.E., Soubias, O., Gawrisch, K. Internal hydration increases during activation of the G-protein-coupled receptor rhodopsin. J. Mol. Biol. 2008, 381, 478-86. 

First, it provides another mechanism of desensitization, in that receptors at the cell surface produce an increase in cAMP via G whereas internalized receptors produce a decrease in cAMP levels via G,. Second, it has been found that Py subunits released from activated G, are capable of stimulating the MAPK cascade. Thus, at least for the P2 receptor, internalization functions not only to temporarily desensitize the receptor to activation of the cAMP pathway but also to initiate signaling to MAPK. Recently, a number of other G protein-coupled receptors have been found to signal to the MAPK pathway via G as well as G and G and many of these receptors seem to require internalization for such signaling to take place. 

S-pBlmrtovI (S-Acy11 tieterotrimeric G-proteins a-sjbunit), G-protein-coupled receptors, see chapter 5 Has proteins, see chapter 8 internal, no distinct consensus sequence... 

Fig. 6.4. Formation and function of diacylglycerol and Ins(l,4,5)P3. Formation of diacylglycerol (DAG) and Ins(l,4,5)P3 is subject to regulation by two central signaling pathways, which start from transmembrane receptors with intrinsic or associated tyrosine kinase activity (see Chapters 8 11) or from G-protein-coupled receptors. DAG activates protein kinase C (PKC, see Chapter 7), which has a regulatory effect on ceU proliferation, via phosphorylation of substrate proteins. Ins(l,4,5)P3 binds to corresponding receptors (InsPs-R) and induces release of Ca from internal stores. The membrane association of DAG, PtdIns(3,4)P2 and PL-C is not shown here, for clarity.

Fan G, Shumay E, Malbon CC, Wang H (2001) c-Src tyrosine kinase binds the beta 2-adrenergic receptor via phospho-Tyr-350, phosphorylates G-protein-linked receptor kinase 2, and mediates agonist-induced receptor desensitization. J Biol Chem 276(16) 13240-13247 Ferguson G, Watterson KR, Palmer TM (2000) Subtype-specific kinetics of inhibitory adenosine receptor internalization are determined by sensitivity to phosphorylation by G protein coupled receptor kinases. Mol Pharmacol 57(3) 546-552... 

---