Efficient coupling of transducin to monomeric rhodopsin in a phospholipid bilayer

Whorton, Matthew R; Jastrzebska, Beata; Park, Paul S-H; Fotiadis, Dimitrios; Engel, Andreas; Palczewski, Krzysztof; Sunahara, Roger K (2008). Efficient coupling of transducin to monomeric rhodopsin in a phospholipid bilayer. Journal of biological chemistry, 283(7), pp. 4387-94. Bethesda, Md.: American Society for Biochemistry and Molecular Biology 10.1074/jbc.M703346200

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G protein-coupled receptors (GPCRs) are seven transmembrane domain proteins that transduce extracellular signals across the plasma membrane and couple to the heterotrimeric family of G proteins. Like most intrinsic membrane proteins, GPCRs are capable of oligomerization, the function of which has only been established for a few different receptor systems. One challenge in understanding the function of oligomers relates to the inability to separate monomeric and oligomeric receptor complexes in membrane environments. Here we report the reconstitution of bovine rhodopsin, a GPCR expressed in the retina, into an apolipoprotein A-I phospholipid particle, derived from high density lipoprotein (HDL). We demonstrate that rhodopsin, when incorporated into these 10 nm reconstituted HDL (rHDL) particles, is monomeric and functional. Rhodopsin.rHDL maintains the appropriate spectral properties with respect to photoactivation and formation of the active form, metarhodopsin II. Additionally, the kinetics of metarhodopsin II decay is similar between rhodopsin in native membranes and rhodopsin in rHDL particles. Photoactivation of monomeric rhodopsin.rHDL also results in the rapid activation of transducin, at a rate that is comparable with that found in native rod outer segments and 20-fold faster than rhodopsin in detergent micelles. These data suggest that monomeric rhodopsin is the minimal functional unit in G protein activation and that oligomerization is not absolutely required for this process.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Biochemistry and Molecular Medicine

UniBE Contributor:

Fotiadis, Dimitrios José

ISSN:

0021-9258

ISBN:

18033822

Publisher:

American Society for Biochemistry and Molecular Biology

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 15:03

Last Modified:

04 May 2014 23:19

Publisher DOI:

10.1074/jbc.M703346200

PubMed ID:

18033822

Web of Science ID:

000253083500073

URI:

https://boris.unibe.ch/id/eprint/27315 (FactScience: 106010)

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