Gamma-aminobutyric acid (GABA) B receptor, 1 (GABBR1) is a receptor for gamma-aminobutyirc acid (GABA), the primary inhibitory neurotransmitter found in the brain. GABBR1 plays an important role in fine-tuning inhibitory synaptic transmission, and altered expression of this receptor may contribute to seizures. It also plays a role in hippocampal long-term potentiation, slow wave sleep, muscle relaxation and antinociception. Furthermore, mutations and polymorphisms in GABBR1 are associated with genetic epilepsy. In immunohistochemistry, GABBR1 has highest membranous and cytoplasmic positivity on neuronal cells throughout the nervous system. In the cerebellum, GABBR1 is primarily found on granule and Purkinnje cells. It is also found at lower levels in most peripheral tissues. References: Proc Natl Acad Sci U S A. 1998 Dec 8;95(25):14991-6, PMID: 9844003; Cerebellum. 2009 Mar;8(1):64-9. doi: 10.1007/s12311-008-0075-3, PMID: 19002745