GNB1/A0069

Beta-1 subunit of guanine nucleotide binding protein (GNB1) is a member of a family of G protein beta subunit proteins, also known as A0069.

Beta-1 subunit of guanine nucleotide binding protein (GNB1) is a member of a family of G protein beta subunit proteins, also known as A0069. G proteins are a vast group of protein complexes involved in transmitting an extracellular signal inside the cell. In an inactive state alpha, beta and gamma subunits are bound together with guanosine diphosphate (GDP). Alpha and gamma subunits are members of large protein families, while the beta subunit family is represented by relatively few members. Messenger RNA for at least two isoforms of the beta subunit have been isolated, and there are potentially more members of this family. G proteins are usually switched-on by binding an activated G protein-linked receptor. Upon activation alpha subunit-bound GDP is exchanged for guanosine triphosphate (GTP) and the alpha subunit is separated into the cytoplasm from the membrane-associated complex of beta and gamma subunits. Usually it is the alpha subunit that is a functional component in transmitting the extracellular signal, however specific functions have also been ascribed to the complex of beta and gamma subunits. GNB1 is a part of many G protein complexes and was found to be widely expressed across most tissues. Beta-1 protein is implicated directly in phototransduction and maintenance of photoreceptors and disruption of the Gnb1 gene is involved in retinal degeneration in mouse models.