RGS9

Regulator of G-protein signalling 9, also known as RGS9, is a human is_associated_with::gene, which codes for a protein involved in regulation of is_associated_with::signal transduction inside cells. Members of the RGS family, such as RGS9, are signaling proteins that suppress the activity of is_associated_with::G proteins by promoting their deactivation.[supplied by OMIM]

There are two splice isoforms of RGS9 with quite different properties and patterns of expression. RGS9-1 is mainly found in the eye and is involved in regulation of phototransduction in rod and cone cells of the is_associated_with::retina, while RGS9-2 is found in the brain, and regulates dopamine and opioid signaling in the is_associated_with::basal ganglia.

RGS9-2 is of particular interest as the most important RGS protein involved in terminating signalling by the is_associated_with::mu opioid receptor (although is_associated_with::RGS4 and is_associated_with::RGS17 are also involved), and is thought to be important in the development of tolerance to opioid drugs. RGS9-deficient mice exhibit some motor and cognitive difficulties however, so inhibition of this protein is likely to cause similar side effects.

RGS9 is differentially regulated by Guanine nucleotide-binding protein subunit beta-5 (is_associated_with::GNB5) via the is_associated_with::DEP domain and DEP helical-extension domain in protein stability and membrane anchor association.