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TRANSPORTERS FROM HUMANS:
Transporter Information:
Name: solute carrier family 15, member 3
Symbol: SLC15A3
TC: 2.A.17.3.2
Locations: 11q12.2
Aliases: PHT2, hPTR3
GenBank: AB020598
Swiss-Prot: Q8IY34
Accession Number: NM_016582
LocusLink51296
PubMed (11336635): Sakata K, Yamashita T, Maeda M, Moriyama Y, Shimada S, Tohyama M. Cloning of a lymphatic peptide/histidine transporter.Biochem J. 2001 May 15;356(Pt 1):53-60. PMID: 11336635 [PubMed - indexed for MEDLINE]

Although peptide transport across the plasma membrane has been characterized well in the kidney and the intestine, the functional relevance of this transport in other organs has not been addressed. Here we report the cloning of a cDNA for a novel peptide/histidine transporter found in the rat (rPHT2), whose mRNA is expressed mainly in the lymphatic system. rPHT2 encodes a protein of 582 amino acids and showed 49% identity with the brain PHT (PHT1) [Yamashita, Shimada, Guo, Sato, Kohmura, Hayakawa, Takagi and Tohyama (1997) J. Biol. Chem. 272, 10205-10211]. rPHT2 mRNA was abundant in lung, spleen and thymus, and detected faintly in brain, liver, adrenal gland and heart by Northern-blot analysis and reverse transcriptase PCR (RT-PCR). Intense signals for the gene were found in immunocytes using in situ hybridization. Ectopic expression of rPHT2 protein in HEK-293T cells and BHK cells was not found on the cell surface, but was found on the lysosomal membrane using light- and electron-microscopic analysis. Recombinant rPHT2 protein reconstituted into liposomes showed proton-dependent transport activity with histidine and histidyl-leucine. These findings suggest that rPHT2 is involved in the protein catabolic pathway in the lymphatic system.

PubMed (11741232): Botka CW, Wittig TW, Graul RC, Nielsen CU, Higaka K, Amidon GL, Sadee W. Human proton/oligopeptide transporter (POT) genes: identification of putativehuman genes using bioinformatics.AAPS PharmSci. 2000;2(2):E16. PMID: 11741232 [PubMed - indexed for MEDLINE]

The proton-dependent oligopeptide transporters (POT) gene family currently consists of approximately 70 cloned cDNAs derived from diverse organisms. In mammals, two genes encoding peptide transporters, PepT1 and PepT2 have been cloned in several species including humans, in addition to a rat histidine/peptide transporter (rPHT1). Because the Candida elegans genome contains five putative POT genes, we searched the available protein and nucleic acid databases for additional mammalian/human POT genes, using iterative BLAST runs and the human expressed sequence tags (EST) database. The apparent human orthologue of rPHT1 (expression largely confined to rat brain and retina) was represented by numerous ESTs originating from many tissues. Assembly of these ESTs resulted in a contiguous sequence covering approximately 95% of the suspected coding region. The contig sequences and analyses revealed the presence of several possible splice variants of hPHT1. A second closely related human EST-contig displayed high identity to a recently cloned mouse cDNA encoding cyclic adenosine monophosphate (cAMP)-inducible 1 protein (gi:4580995). This contig served to identify a PAC clone containing deduced exons and introns of the likely human orthologue (termed hPHT2). Northern analyses with EST clones indicated that hPHT1 is primarily expressed in skeletal muscle and spleen, whereas hPHT2 is found in spleen, placenta, lung, leukocytes, and heart. These results suggest considerable complexity of the human POT gene family, with relevance to the absorption and distribution of cephalosporins and other peptoid drugs.

>sp|Q8IY34|S15A3_HUMAN Solute carrier family 15 member 3 OS=Homo sapiens GN=SLC15A3 PE=1 SV=2
MPAPRAREQPRVPGERQPLLPRGARGPRRWRRAAGAAVLLVEMLERAAFFGVTANLVLYLNSTNFNWTGEQATRAALVFL
GASYLLAPVGGWLADVYLGRYRAVALSLLLYLAASGLLPATAFPDGRSSFCGEMPASPLGPACPSAGCPRSSPSPYCAPV
LYAGLLLLGLAASSVRSNLTSFGADQVMDLGRDATRRFFNWFYWSINLGAVLSLLVVAFIQQNISFLLGYSIPVGCVGLA
FFIFLFATPVFITKPPMGSQVSSMLKLALQNCCPQLWQRHSARDRQCARVLADERSPQPGASPQEDIANFQVLVKILPVM
VTLVPYWMVYFQMQSTYVLQGLHLHIPNIFPANPANISVALRAQGSSYTIPEAWLLLANVVVVLILVPLKDRLIDPLLLR
CKLLPSALQKMALGMFFGFTSVIVAGVLEMERLHYIHHNETVSQQIGEVLYNAAPLSIWWQIPQYLLIGISEIFASIPGL
EFAYSEAPRSMQGAIMGIFFCLSGVGSLLGSSLVALLSLPGGWLHCPKDFGNINNCRMDLYFFLLAGIQAVTALLFVWIA
GRYERASQGPASHSRFSRDRG