|BCCT family transporter|
BetP (betaine transporter) from Cornyebacterium glutamicum. PDB 3p03
Betaine / Carnitine / Choline Transporters (BCCT) are a family of prokaryotic transport proteins that are specific for compounds containing a quaternary nitrogen atom. The BCCT proteins contain 12 transmembrane regions and are energized by sodium symport. They contain a conserved region with four tryptophans in their central region. All structures solved to date are trimeric.
The mammalian betaine transporter (BGT1; SLC6A12) is predominantly expressed in the liver (hepatocytes). It is also expressed in the kidney where it is regulated by NFAT5 during response to osmotic stress. Further, BGT1 is also present in the leptomeninges surrounding the brain. Deletion of the BGT1 gene in mice did not appear to have any impact on the tendency to develop epilepsy. This is to be expected considering that BGT1 is expressed at far lower levels than GAT1 and also has lower affinity for GABA. This implies that it is not likely to contribute significantly to the inactivation of the inhibitory neurotransmitter GABA.
- Kempf B, Bremer E, Kappes RM (1996). "Three transport systems for the osmoprotectant glycine betaine operate in Bacillus subtilis: characterization of OpuD". J. Bacteriol. 178 (17): 5071–5079. PMC 178300. PMID 8752321.
- Zhou Y, Holmseth S, Hua R, Lehre AC, Olofsson AM, Poblete-Naredo I, Kempson SA, Danbolt NC (2012). "The betaine-GABA transporter (BGT1, slc6a12) is predominantly expressed in the liver and at lower levels in the kidneys and at the brain surface". Am J Physiol Renal Physiol 302 (3): F316–28. doi:10.1152/ajprenal.00464.2011. PMID 22071246.
- Lee SD, Choi SY, Lim SW, Lamitina ST, Ho SN, Go WY, Kwon HM (2011). "TonEBP stimulates multiple cellular pathways for adaptation to hypertonic stress: Organic osmolyte-dependent and -independent pathways". AJP: Renal Physiology 300 (3): F707–F715. doi:10.1152/ajprenal.00227.2010. PMC 3064130. PMID 21209002.
- Lehre AC, Rowley NM, Zhou Y, Holmseth S, Guo C, Holen T, Hua R, Laake P, Olofsson AM, Poblete-Naredo I, Rusakov DA, Madsen KK, Clausen RP, Schousboe A, White HS, Danbolt NC (2011). "Deletion of the betaine-GABA transporter (BGT1; slc6a12) gene does not affect seizure thresholds of adult mice". Epilepsy Res 95 (1-2): 70–81. doi:10.1016/j.eplepsyres.2011.02.014. PMID 21459558.
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