regulator of G-protein signaling 9 (RGS9)

Function

• inhibits signal transduction by increasing GTPase activity of G-alpha subunits thus increasing the amount of inactive GDP-bound form
  • binds to Gt-alpha
  • role in phototransduction recovery phase (putative)
  • retinal isoform 3 is light-dependent phosphorylated at Ser-478
  • phosphorylation is decreased by light exposition
  • heterodimer with Gbeta5
  • interacts with RGS9BP, regulating the subcellular location RGS9/Gbeta5 heterodimer
  • component of the RGS9-1-Gbeta5 complex composed of isoform 3 of RGS9 (RGS9-1), Gbeta5 (GNB5) & RGS9BP (probable)

Structure

• in photoreceptor cells the DEP domain is essential for targeting RGS9 to the outer rod segments
• contains 1 DEP domain
• contains 1 G protein gamma domain
• contains 1 RGS domain

Compartment

• isoform 3: membrane; peripheral membrane protein.
• isoform 3 is targeted to the membrane via its interaction with RGS9BP (putative)

Alternative splicing

named isoforms=5

Expression

• highly expressed in the caudate & putamen,
• lower levels found in the hypothalamus & nucleus accumbens
• very low levels in cerebellum
• not expressed in globus pallidus or cingulate cortex
• isoform 2 is expressed predominantly in pineal gland & retina
• isoform 3 is expressed in retina (abundant in photoreceptors)

Pathology

• defects in RGS9 are a cause of prolonged electroretinal response suppression (bradyopsia)

More general terms

• regulator of G-protein signaling

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=8787
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:8787
• OMIM: https://mirror.omim.org/entry/604067
• OMIM: https://mirror.omim.org/entry/608415
• UniProt: http://www.uniprot.org/uniprot/O75916.html