|Name:||solute carrier family 7 (cationic amino acid transporter, y+ system), member 8|
|PubMed (10080183):|| Borsani G, Bassi MT, Sperandeo MP, De Grandi A, Buoninconti A, Riboni M,Manzoni M, Incerti B, Pepe A, Andria G, Ballabio A, Sebastio G. SLC7A7, encoding a putative permease-related protein, is mutated in patientswith lysinuric protein intolerance.Nat Genet. 1999 Mar;21(3):297-301. PMID: 10080183 [PubMed - indexed for MEDLINE]|
Lysinuric protein intolerance (LPI, MIM 222700) is an autosomal recessive multisystem disorder found mainly in Finland and Italy. On a normal diet, LPI patients present poor feeding, vomiting, diarrhoea, episodes of hyperammoniaemic coma and failure to thrive. Hepatosplenomegaly, osteoporosis and a life-threatening pulmonary involvement (alveolar proteinosis) are also seen. LPI is caused by defective cationic amino acid (CAA) transport at the basolateral membrane of epithelial cells in kidney and intestine. Metabolic derangement is characterized by increased renal excretion of CAA, reduced CAA absorption from intestine and orotic aciduria. The gene causing LPI was assigned using linkage analysis to chromosome 14q11.2 near the T-cell receptor alpha/delta chains locus, and a critical region has been defined. We have identified two new transcripts (SLC7A8 and SLC7A7) homologous to amino acid transporters, highly expressed in kidney and mapping in the LPI critical region. Mutational analysis of both transcripts revealed that SLC7A7 (for solute carrier family 7, member 7) is mutated in LPI. In five Italian patients, we found either an insertion or deletion in the coding sequence, which provides evidence of a causative role of SLC7A7 in LPI. Furthermore, we detected a splice acceptor change resulting in a frameshift and premature translation termination in four unrelated Finnish patients. This mutation may represent the founder LPI allele in Finland.
|PubMed (10391915):|| Pineda M, Fernandez E, Torrents D, Estevez R, Lopez C, Camps M, Lloberas J,Zorzano A, Palacin M. Identification of a membrane protein, LAT-2, that Co-expresses with 4F2 heavychain, an L-type amino acid transport activity with broad specificity for smalland large zwitterionic amino acids.J Biol Chem. 1999 Jul 9;274(28):19738-44. PMID: 10391915 [PubMed - indexed for MEDLINE]|
We have identified a new human cDNA, L-amino acid transporter-2 (LAT-2), that induces a system L transport activity with 4F2hc (the heavy chain of the surface antigen 4F2, also named CD98) in oocytes. Human LAT-2 is the fourth member of the family of amino acid transporters that are subunits of 4F2hc. The amino acid transport activity induced by the co-expression of 4F2hc and LAT-2 was sodium-independent and showed broad specificity for small and large zwitterionic amino acids, as well as bulky analogs (e.g. BCH (2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid)). This transport activity was highly trans-stimulated, suggesting an exchanger mechanism of transport. Expression of tagged N-myc-LAT-2 alone in oocytes did not induce amino acid transport, and the protein had an intracellular location. Co-expression of N-myc-LAT-2 and 4F2hc gave amino acid transport induction and expression of N-myc-LAT-2 at the plasma membrane of the oocytes. These data suggest that LAT-2 is an additional member of the family of 4F2 light chain subunits, which associates with 4F2hc to express a system L transport activity with broad specificity for zwitterionic amino acids. Human LAT-2 mRNA is expressed in kidney >>> placenta >> brain, liver > spleen, skeletal muscle, heart, small intestine, and lung. Human LAT-2 gene localizes at chromosome 14q11.2-13 (13 cR or approximately 286 kb from marker D14S1349). The high expression of LAT-2 mRNA in epithelial cells of proximal tubules, the basolateral location of 4F2hc in these cells, and the amino acid transport activity of LAT-2 suggest that this transporter contributes to the renal reabsorption of neutral amino acids in the basolateral domain of epithelial proximal tubule cells.
>sp|Q9UHI5|LAT2_HUMAN Large neutral amino acids transporter small subunit 2 OS=Homo sapiens GN=SLC7A8 PE=1 SV=1 MEEGARHRNNTEKKHPGGGESDASPEAGSGGGGVALKKEIGLVSACGIIVGNIIGSGIFVSPKGVLENAGSVGLALIVWI VTGFITVVGALCYAELGVTIPKSGGDYSYVKDIFGGLAGFLRLWIAVLVIYPTNQAVIALTFSNYVLQPLFPTCFPPESG LRLLAAICLLLLTWVNCSSVRWATRVQDIFTAGKLLALALIIIMGIVQICKGEYFWLEPKNAFENFQEPDIGLVALAFLQ GSFAYGGWNFLNYVTEELVDPYKNLPRAIFISIPLVTFVYVFANVAYVTAMSPQELLASNAVAVTFGEKLLGVMAWIMPI SVALSTFGGVNGSLFTSSRLFFAGAREGHLPSVLAMIHVKRCTPIPALLFTCISTLLMLVTSDMYTLINYVGFINYLFYG VTVAGQIVLRWKKPDIPRPIKINLLFPIIYLLFWAFLLVFSLWSEPVVCGIGLAIMLTGVPVYFLGVYWQHKPKCFSDFI ELLTLVSQKMCVVVYPEVERGSGTEEANEDMEEQQQPMYQPTPTKDKDVAGQPQP