Pajor Ana M
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, TX 77555, USA.
Pflugers Arch. 2006 Feb;451(5):597-605. doi: 10.1007/s00424-005-1487-2. Epub 2005 Oct 7.
The SLC13 gene family consists of five members in humans, with corresponding orthologs from different vertebrate species. All five genes code for sodium-coupled transporters that are found on the plasma membrane. Two of the transporters, NaS1 and NaS2, carry substrates such as sulfate, selenate and thiosulfate. The other members of the family (NaDC1, NaDC3, and NaCT) are transporters for di- and tri-carboxylates including succinate, citrate and alpha-ketoglutarate. The SLC13 transporters from vertebrates are electrogenic and they produce inward currents in the presence of sodium and substrate. Substrate-independent leak currents have also been described. Structure-function studies have identified the carboxy terminal half of these proteins as the most important for determining function. Transmembrane helices 9 and 10 may form part of the substrate permeation pathway and participate in conformational changes during the transport cycle. This review also discusses new members of the SLC13 superfamily that exhibit both sodium-dependent and sodium-independent transport mechanisms. The Indy protein from Drosophila, involved in determining lifespan, and the plant vacuolar malate transporter are both sodium-independent dicarboxylate transporters, possibly acting as exchangers. The purpose of this review is to provide an update on new advances in this gene family, particularly on structure-function studies and new members of the family.
SLC13基因家族在人类中由五个成员组成，在不同脊椎动物物种中有相应的直系同源基因。所有这五个基因编码的是位于质膜上的钠偶联转运蛋白。其中两个转运蛋白，即NaS1和NaS2，负责转运诸如硫酸盐、硒酸盐和硫代硫酸盐等底物。该家族的其他成员（NaDC1、NaDC3和NaCT）则是二羧酸盐和三羧酸盐的转运蛋白，包括琥珀酸盐、柠檬酸盐和α-酮戊二酸。脊椎动物的SLC13转运蛋白是生电的，在有钠和底物存在时会产生内向电流。也有关于不依赖底物的泄漏电流的描述。结构-功能研究已确定这些蛋白质的羧基末端一半对于确定功能最为重要。跨膜螺旋9和10可能构成底物渗透途径的一部分，并在转运循环中参与构象变化。本综述还讨论了SLC13超家族的新成员，它们表现出依赖钠和不依赖钠的转运机制。果蝇中参与确定寿命的Indy蛋白和植物液泡苹果酸转运蛋白都是不依赖钠的二羧酸盐转运蛋白，可能作为交换体发挥作用。本综述的目的是提供该基因家族新进展的最新情况，特别是关于结构-功能研究和该家族新成员的情况。
