RGS9BP (regulator of G protein signaling 9 binding protein) is a membrane-anchoring protein essential for phototransduction recovery in retinal photoreceptors. It localizes RGS9-1 to the photoreceptor outer segment and enhances its GTPase-stimulating activity, enabling timely termination of visual signals 1. RGS9BP also protects RGS9-1 from proteolytic degradation, stabilizing this critical signaling regulator. Pathogenic variants in RGS9BP cause bradyopsia, characterized by abnormally prolonged electroretinal response suppression 2, representing a monogenic inherited retinal disease associated with cone dysfunction 1. Clinical cases demonstrate that RGS9BP mutations can present as incomplete achromatopsia-like phenotypes, requiring differentiation through genetic testing and phenotypic reassessment 3. Targeted exome sequencing studies have identified RGS9BP mutations in patients with cone and cone-rod dystrophies 4, confirming its role in phototransduction-dependent retinal health. Beyond vision, RGS9BP appears implicated in broader GPCR signaling pathways with potential relevance to reproductive function in mammals 5, though its primary characterized function remains visual signal termination through G protein regulation in photoreceptor cells.