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Abstract
G protein-coupled receptors (GPCRs) mediate essential transmembrane signaling, requiring precise attenuation by regulatory proteins. This work examines interactions between rhodopsin and its modulators, including arrestins and rhodopsin kinase (RK). We show that both visual and β-arrestin 1 preferentially bind monomeric rhodopsin in nanodiscs, and RK phosphorylates monomeric rhodopsin via a conserved binding region shared with transducin. Fluorescence studies identified two arrestin sites interacting with rhodopsin’s TM6 base. Additionally, initial characterization of CRIP1a, a CB1 receptor modulator, revealed high β-sheet content and stability, with ongoing crystallization efforts. These findings advance understanding of GPCR signal termination and structural regulation.