Sulfate transport by SLC26 transporters.
ABSTRACT Sulfate is the fourth most abundant anion in human plasma that is essential for numerous physiological functions, including biotransformation of xenobiotics, steroids, non-steroidal anti-inflammatory drugs (NSAIDs), adrenergic stimulants/blockers and analgesics. Sulfate is also required for activation of many endogenous compounds (heparin, heparan sulfate, dermatan sulfate, bile acids) and utilized in the metabolism of neurotransmitters. Sulfation of structural components, including glycosaminoglycans and cerebroside sulfate, is essential for the maintenance of normal structure and function of tissues. Due to its hydrophilic nature, sulfate cannot readily cross the lipid bilayer of cells, thus plasma membrane proteins, known as sulfate transporters, are required for the movement of sulfate into/out of cells. Sulfate transporters can be divided into two distinct groups: Na+-dependent sulfate transporters belonging to the SLC13 gene family and Na+-independent sulfate transporters (antiporters, exchangers) belonging to SLC26 gene family. There are 11 members of the SLC26 family (including Sat1, DTDST, CLD, pendrin, prestin, cfex) whose structures and functions have been only partially characterized. In this presentation, the current information on the structures and functions of the sulfate transporters in the SLC26 gene family will be described and the issue that certain members of this family are unable to transport sulfate, will be addressed.