RGS8 (regulator of G protein signaling 8) is a neuron-specific protein that modulates G protein-coupled receptor signaling by accelerating the GTPase activity of G protein alpha subunits, thereby promoting their transition to the inactive GDP-bound state 1. RGS8 exhibits tissue-specific expression, being physiologically expressed in cerebellar Purkinje cells and functioning as a critical regulator of mGluR1 signaling pathways 2. The protein forms stable physical interactions with heterotrimeric G proteins, participating in ternary complexes that influence both activation and deactivation kinetics of G protein signaling 1. RGS8 undergoes dynamic subcellular localization, translocating from the nucleus to the plasma membrane upon G protein activation through direct association with Galpha subunits 3. Clinically, RGS8 has emerged as a significant autoantibody target in paraneoplastic cerebellar ataxia, particularly associated with specific subtypes of lymphoma including nodular lymphocyte-predominant Hodgkin lymphoma 45. These RGS8 autoantibodies cause severe, treatment-resistant cerebellar ataxia in predominantly middle-aged males 4. Additionally, RGS8 dysregulation occurs in spinocerebellar ataxia type 2 (SCA2), where mutant ATXN2 impairs RGS8 mRNA translation, contributing to cerebellar dysfunction through altered mGluR1-ITPR1 signaling 2.