Cloning of a lymphatic peptide/histidine transporter

Biochemical Journal - Tập 356 Số 1 - Trang 53-60 - 2001
Kazuko Sakata1,2, Toshihide Yamashita3, Mitsuyo MAEDA4, Yoshinori Moriyama5, Shoichi Shimada6, Masaya TOHYAMA1,2
1Core Research for Evolutional Science and Technology (CREST), Kawagutchi 332-0012, Japan
2Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
3Department of Neurobiochemistry, Max-Planck Institute of Neurobiology, Am Klopferspitz 18a, D-82152, Martinsried, Germany
4First Department of Anatomy, Osaka City University Medical School, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan
5Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, 1-1-1 Thushimanaka, Okayama 700-8530, Japan
6Second Department of Anatomy, Nagoya City University Medical School, 1 Kawasumi Mizuho, Mizuho, Nagoya 467-0001, Japan

Tóm tắt

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.

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Biochemical Journal

Tập 356 Số 1

53-60

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