The NHX family of Na+-H+ exchangers in Caenorhabditis elegans.

摘要: Abstract Na+-H+ exchangers prevent cellular acidification by catalyzing the electroneutral exchange of extracellular sodium for an intracellular proton. To date, seven have been identified in mammals, and although several members this family extensively studied characterized, it is clear that there are major gaps our understanding with respect to remaining members. initiate study a genomically defined genetically tractable model system, we cloned complete cDNAs analyzed splice site variation nine putative homologs from nematode Caenorhabditis elegans, which called NHX-1 through -9. The expression patterns distributions NHX proteins were determined using transcriptional translational promoter-transgene fusion constructs green fluorescent protein. Four expressed at cell surface, whereas five associated membranes organelles. Individual isoforms exclusively intestine, seam cells, hypodermal cells main body syncytium, excretory cell, all polarized epithelial suggesting role these membrane transport processes nematode. Other found express either ubiquitously or pan-neural pattern, more conserved pH regulation neuronal function. Finally, show recombinant NHX-4, ubiquitous exchanger, mediates Na+-dependent recovery after acidification. NHX-4 has K Na+of ∼32 mm, not Cl−-dependent, relatively insensitive amiloride analog EIPA.