Abstract

This literature review examines the biochemical mechanisms underlying rhodopsin activation, transducin coupling, and signal termination in phototransduction. Rhodopsin, a rod cell GPCR, undergoes conformational changes upon 11-cis-retinal chromophore isomerization, leading to the activation of transducin (Gt) and subsequent downstream signaling. Structural studies— including X-ray crystallography, time resolved serial femtosecond crystallography, and cryogenic electron microscopy—have provided insights into the transitions between inactive and active rhodopsin states and the binding interface between rhodopsin and transducin.This review synthesizes recent findings on the molecular basis of transducin binding, including key conformational shifts (at the residual and macromolecule level) in rhodopsin’s transmembrane helices that propagate to the cytoplasmic face. Additionally, the role of rhodopsin kinase (GRK1) and arrestin in signal termination and receptor desensitization is explored. Despite significant advances, gaps remain in understanding the precise mechanism of transducin translocation. Emerging studies, particularly in the computational realm, are refining models of GPCR and G-protein interaction.By integrating structural and biochemical perspectives, this review highlights current advancements and unresolved questions in rhodopsin-mediated phototransduction. In doing so, it provides key insights into the biochemical framework for rhodopsin-transducin mediated signal transduction, with implications for understanding broader GPCR signaling mechanisms.

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