Identification of a high affinity taurine transporter which is not dependent on chloride.
Taurine transport by lactating gerbil mammary tissue has been examined. Taurine uptake is mediated by a high-affinity system which is specific for beta-amino acids. The uptake of taurine is Na(+)-dependent but appears not to be obligatory dependent upon Cl-. Thus, replacing Na+ with choline almost abolished taurine uptake. Substituting Cl- with NO3- had no effect whereas SCN- induced a small but significant increase in taurine influx. Taurine uptake was Na(+)-dependent under conditions where Cl- had been replaced with NO3-. However, it is apparent that the Na(+)-dependent taurine transport system requires the presence of a permeable anion because replacing Cl- with gluconate markedly reduced taurine uptake. Cell-swelling, induced by a hyposmotic challenge, increased the efflux of taurine from gerbil mammary tissue via a pathway sensitive to niflumic acid.
Shennan
D B
DB
Hannah Research Institute, United Kingdom.
D000818:Animals; D000838:Anions / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D002352:Carrier Proteins / Q000302:isolation & purification*; D048429:Cell Size / Q000502:physiology; D002712:Chlorides / Q000494:pharmacology*; D005260:Female; D005849:Gerbillinae; D007700:Kinetics; D007774:Lactation / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000302:isolation & purification*; D026901:Membrane Transport Proteins; D012964:Sodium / Q000378:metabolism; D013379:Substrate Specificity; D013654:Taurine / Q000378:metabolism*; D013997:Time Factors; D000099247:Taurine Transporters
D000838:Anions; D002352:Carrier Proteins; D002712:Chlorides; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D012964:Sodium; D013654:Taurine; D000099247:Taurine Transporters