SNAT3

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SNAT3 or SLC38A3 was previously referred to as S ystem N (SN1) or NAT transporter. The original designation based on the substrate specificity, since SNAT3 n eutrale A minosäuren t ransportiert, a nitrogen group (chemical symbol N carry) in their radical. SNAT3 is mainly found in the liver, where it makes glutamine available for the synthesis of urea , but it is also found in the brain and kidneys.

nomenclature

In the course of genome decoding , the previously deliberately assigned protein names for SNAT3 were divided into gene families on the basis of homology . Today, proteins are either only named with the short form of the gene family, or with a uniform short version that is related to their properties.

properties

SNAT3 is a sodium-dependent, neutral amino acid transporter, which mainly transports glutamine , which is very important for humans , but also asparagine and histidine . The stoichiometry is 1 Na +: 1Gln in the symport, 1H + in the antiport, which arithmetically results in an electronically neutral transport. In the Xenopus oocyte expression system, however, SNAT3 shows inward cation conductivity during amino acid transport. This conductivity proves to be sensitive to carbonic anhydrase II, which suppresses the glutamine-induced conductivity when it is catalytically active.

pathology

SNAT3 knock-out mice cannot survive longer than 14 days postnatally. Since another System N transporter, SNAT5 , exists in the brain and liver and there is no inhibitor for SNAT3 on the market, no clear dependency e.g. B. hepatic encephalopathy can be detected by the activity of SNAT3. However, SNAT3 is an acid / base transporter due to the proton membrane transport and thus contributes to the pH value homeostasis. It has been shown to be altered in its tissue expression in acidosis . This could be demonstrated for the kidneys in the form of an upregulation and for glioma cells in cell culture in the form of a downregulation.

swell

  1. ↑ Boulland JL, Osen KK, Levy LM, Danbolt NC, Edwards RH, Storm-Mathisen J, Chaudhry FA: Cell-specific expression of the glutamine transporter SN1 suggests differences in dependence on the glutamine cycle . In: Eur J Neurosci . 15, No. 10, 2002, pp. 1615-1631. doi : 10.1046 / j.1460-9568.2002.01995.x . PMID 12059969 .
  2. ↑ Moret C, Dave MH, Schulz N, Jiang JX, Verrey F, Wagner CA .: Regulation of renal amino acid transporters during metabolic acidosis. . In: Am J Physiol Renal Physiol . 292, No. 2, 2007, pp. F555-66. doi : 10.1152 / ajprenal.00113.2006 . PMID 17003226 .
  3. ↑ Bröer A, Albers A, Setiawan I, Edwards RH, Chaudhry FA, ​​Lang F, Wagner CA, Bröer S: Regulation of the glutamine transporter SN1 by extracellular pH and intracellular sodium ions. . In: J Physiol . 15, No. 539, 2002, pp. 3-14. doi : 10.1113 / jphysiol.2001.013303 . PMID 11850497 .
  4. ↑ Schneider HP, Bröer S, Bröer A, Deitmer JW: Heterologous expression of the glutamine transporter SNAT3 in Xenopus oocytes is associated with four modes of uncoupled transport. . In: J Biol Chem . 282, No. 6, 2007, pp. 3788-3798. doi : 10.1074 / jbc.M609452200 . PMID 17148440 .
  5. ↑ Weise A, Becker HM, Deitmer JW: Enzymatic suppression of the membrane conductance associated with the glutamine transporter SNAT3 expressed in Xenopus oocytes by carbonic anhydrase II . In: J Gen Physiol . 130, No. 2, 2007, pp. 203-215. doi : 10.1085 / jgp.200709809 . PMID 17664347 .
  6. ↑ Cubelos B, González-González IM, Giménez C, Zafra F: Amino acid transporter SNAT5 localizes to glial cells in the rat brain. . In: Glia . 49, No. 2, 2005, pp. 230-244. doi : 10.1002 / glia.20106 . PMID 15390093 .
  7. ↑ Baird FE, Beattie KJ, Hyde AR, Ganapathy V, Rennie MJ, Taylor PM: Bidirectional substrate fluxes through the system N (SNAT5) glutamine transporter may determine net glutamine flux in rat liver. . In: J Physiol . 559, No. 2, 2004, pp. 367-381. doi : 10.1113 / jphysiol.2003.060293 . PMID 15218073 .
  8. ↑ Busque SM, Wagner CA: Potassium restriction, high protein intake, and metabolic acidosis increase expression of the glutamine transporter SNAT3 (Slc38a3) in mouse kidney. . In: Am J Physiol-Renal Physiol . 297, No. 2, 2009, pp. F440-F450. doi : 10.1152 / ajprenal.90318.2008 . PMID 19458124 .
  9. ↑ Sidoryk M, Obara M, Albrecht J: Selective decrease of SN1 (SNAT3) mRNA expression in human and rat glioma cells adapted to grow in acidic medium. . In: Neurochem Int . 48, No. 6-7, 2006, pp. 547-552. doi : 10.1016 / j.neuint.2005.12.026 . PMID 16513216 .