Human/Mouse/Rat GABA_B R1 Antibody

GABA_B R1 (GABA-B receptor subunit 1; also GABA-BR1, GABBR1 and GB1) is a multispan member of the GABA-B receptor subfamily, GPCR-3 family of proteins. It forms an obligatory heterodimer with GABA-BR2, creating a G-protein metabotropic GABA receptor that inhibits adenylyl cyclase activity and activates K⁺ channels. Presynaptically, this blocks neurotransmitter release; postsynaptically, it lowers neuron excitability. Rat GABA_B R1 is 991 amino acids (aa) in length. It is a 7‑transmembrane glycoprotein that contains a 16 aa signal sequence, an extended N‑terminal extracellular region (aa 17-590) that contains two SUSHI domains (aa 29‑158), and a long C-terminal cytoplasmic domain (aa 885-991). There are several splice variants with predicted molecular weights ranging from 90 to 111 kDa and multiple glycosylation sites. The 991 aa isoform described above is called GABA_B R1e (R1e). There is also a 960 aa, 130 kDa isoform that shows a deletion of aa 771‑801. This variant (R1a) is associated with postsynaptic membranes. A third isoform (R1b) is 844 aa in length and 100 kDa in size, and possesses both a deletion of aa 771-801, and a 47 aa substitution for aa 1-163. This variant is presynaptic in location. Two other isoforms are variants of GABA_B R1b. Each show the same N‑terminal substitution, with a fourth isoform (R1c) retaining aa 771-801, and a fifth isoform (R1d) deleting aa 771-801, coupled to a 25 aa substitution for aa 935‑991. Over aa 17-586, rat GABA_B R1e/a shares 99% aa identity with both mouse and human GABA_B R1.