X-Transporter protein 3 (Xtrp3)

Na(+) and Cl(-)-coupled transporter proteins mediate transit of structurally related small hydrophilic substances across plasma membranes. These transporters are structurally related to a small subgroup of proteins with no known substrates.Sequence analysis predicted that the mouse sequence, approximately 88% identical to human XT3 and rat B21a, contains 12 potential transmembrane domains. Northern blot analysis detected 3.2- and 4.0-kb XT3 transcripts in human kidney and small intestine, with no expression detected in other tissues. Expression was slightly higher in kidney, where an 8.5-kb transcript was also detected. Immunofluorescence microscopy demonstrated expression on the plasma membrane of transfected cells.