|GABAB R1 in Rat Trigeminal Ganglia. GABAB R1 was detected in perfusion fixed frozen sections of rat trigeminal ganglia using Mouse Anti-Rat GABAB R1 Monoclonal Antibody (Catalog # MAB7000) at 25 µg/mL overnight at 4 °C. Tissue was stained using the NorthernLights™ 557-conjugated Anti-Mouse IgG Secondary Antibody (red; Catalog # NL007) and counterstained with DAPI (blue). Specific staining was localized to plasma membranes and cytoplasm of sensory neurons. View our protocol for Fluorescent IHC Staining of Frozen Tissue Sections.|
GABAB R1 (GABA-B receptor subunit 1; also GABA-BR1, GABBR1 and GB1) is a multispan glycoprotein in 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 GABAB R1 is 991 amino acids (aa) in length. It 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 GABAB 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 GABAB 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 GABAB R1e/a shares 99% aa identity with both mouse and human GABAB R1.