Publications

• Molecular cloning of the mouse IMINO system: an Na(+)- and Cl(-)-dependent proline transporter.

  Kowalczuk S., Broeer A., Munzinger M., Tietze N., Klingel K., Broeer S.

  Neurotransmitter transporters of the SLC6 family play an important role in the removal of neurotransmitters in brain tissue and in amino acid transport in epithelial cells. Here we demonstrate that the mouse homologue of slc6a20 has all properties of the long-sought IMINO system. The mouse has two ... >> More

  Neurotransmitter transporters of the SLC6 family play an important role in the removal of neurotransmitters in brain tissue and in amino acid transport in epithelial cells. Here we demonstrate that the mouse homologue of slc6a20 has all properties of the long-sought IMINO system. The mouse has two homologues corresponding to the single human SLC6A20 gene: these have been named XT3 and XT3s1. Expression of mouse XT3s1, but not XT3, in Xenopus laevis oocytes induced an electrogenic Na+-and-Cl--dependent transporter for proline, hydroxyproline, betaine, N-methylaminoisobutyric acid and pipecolic acid. Expression of XT3s1 was found in brain, kidney, small intestine, thymus, spleen and lung, whereas XT3 prevailed in kidney and lung. Accordingly we suggest that the two homologues be termed 'XT3s1 IMINO(B)' and 'XT3 IMINO(K)' to indicate the tissue expression of the two genes. << Less

  Biochem. J. 386:417-422(2005) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• L-proline and L-pipecolate induce enkephalin-sensitive currents in human embryonic kidney 293 cells transfected with the high-affinity mammalian brain L-proline transporter.

  Galli A., Jayanthi L.D., Ramsey I.S., Miller J.W., Fremeau R.T. Jr., DeFelice L.J.

  The high-affinity mammalian brain L-proline transporter (PROT) belongs to the GAT1 gene family, which includes Na- and Cl-dependent plasma membrane carriers for neurotransmitters, osmolites, and metabolites. These transporters couple substrate flux to transmembrane electrochemical gradients, parti ... >> More

  The high-affinity mammalian brain L-proline transporter (PROT) belongs to the GAT1 gene family, which includes Na- and Cl-dependent plasma membrane carriers for neurotransmitters, osmolites, and metabolites. These transporters couple substrate flux to transmembrane electrochemical gradients, particularly the Na gradient. In the nervous system, transporters clear synapses and help to replenish transmitters in nerve terminals. The localization of PROT to specific excitatory terminals in rat forebrain suggests a role for this carrier in excitatory transmission (). We investigated the voltage regulation and electrogenicity of this novel transporter, using human embryonic kidney (HEK) 293 cells stably transfected with rat PROT cDNA. In physiological solutions between -140 and -40 mV, L-proline (PRO) and its six-member ring congener L-pipecolate (PIP) induced inward current. The current-voltage relationship and the variance of current fluctuations were similar for PRO- and PIP-induced current, and the ratio of induced variance to the mean current ranged from 20 to 60 fA. Des-Tyr-Leu-enkephalin (GGFL), a competitive peptide inhibitor of PROT, reduced the rat PROT-associated current to control levels. GGFL alone did not elicit currents, and the GGFL-sensitive substrate-induced current was absent in nontransfected cells. Finally, GGFL inhibited PROT-mediated transport only when applied to the extracellular face of PROT. These data suggest that (1) PROT uptake is electrogenic, (2) individual transporter currents are voltage-independent, and (3) GGFL is a nonsubstrate inhibitor that interacts either with an extracellular domain of PROT or in an externally accessible pore. << Less

  J. Neurosci. 19:6290-6297(1999) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.