Structural highlights
Function
[OPSD_BOVIN] Photoreceptor required for image-forming vision at low light intensity. Required for photoreceptor cell viability after birth. Light-induced isomerization of 11-cis to all-trans retinal triggers a conformational change leading to G-protein activation and release of all-trans retinal (By similarity).[1] [2] [GNAT1_BOVIN] Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. Transducin is an amplifier and one of the transducers of a visual impulse that performs the coupling between rhodopsin and cGMP-phosphodiesterase. [GBB1_BOVIN] Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction.
Publication Abstract from PubMed
Rhodopsin (Rho), a prototypical G-protein-coupled receptor (GPCR) in vertebrate vision, activates the G-protein transducin (GT) by catalyzing GDP-GTP exchange on its alpha subunit (GalphaT). To elucidate the determinants of GT coupling and activation, we obtained cryo-EM structures of a fully functional, light-activated Rho-GT complex in the presence and absence of a G-protein-stabilizing nanobody. The structures illustrate how GT overcomes its low basal activity by engaging activated Rho in a conformation distinct from other GPCR-G-protein complexes. Moreover, the nanobody-free structures reveal native conformations of G-protein components and capture three distinct conformers showing the GalphaT helical domain (alphaHD) contacting the Gbetagamma subunits. These findings uncover the molecular underpinnings of G-protein activation by visual rhodopsin and shed new light on the role played by Gbetagamma during receptor-catalyzed nucleotide exchange.
Structures of the Rhodopsin-Transducin Complex: Insights into G-Protein Activation.,Gao Y, Hu H, Ramachandran S, Erickson JW, Cerione RA, Skiniotis G Mol Cell. 2019 Jun 24. pii: S1097-2765(19)30440-X. doi:, 10.1016/j.molcel.2019.06.007. PMID:31300275[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Nakamichi H, Okada T. Local peptide movement in the photoreaction intermediate of rhodopsin. Proc Natl Acad Sci U S A. 2006 Aug 22;103(34):12729-34. Epub 2006 Aug 14. PMID:16908857
- ↑ Salom D, Lodowski DT, Stenkamp RE, Le Trong I, Golczak M, Jastrzebska B, Harris T, Ballesteros JA, Palczewski K. Crystal structure of a photoactivated deprotonated intermediate of rhodopsin. Proc Natl Acad Sci U S A. 2006 Oct 31;103(44):16123-8. Epub 2006 Oct 23. PMID:17060607
- ↑ Gao Y, Hu H, Ramachandran S, Erickson JW, Cerione RA, Skiniotis G. Structures of the Rhodopsin-Transducin Complex: Insights into G-Protein Activation. Mol Cell. 2019 Jun 24. pii: S1097-2765(19)30440-X. doi:, 10.1016/j.molcel.2019.06.007. PMID:31300275 doi:http://dx.doi.org/10.1016/j.molcel.2019.06.007
