L-type amino acid transporter-1 expressed in human astrocytomas, U343MGa.
LAT1 (L-type amino acid transporter 1), one of the L-type amino acid transporters, transports the branched and aromatic amino acids. LAT1 requires the heavy chain of 4F2 antigen (4F2hc) for the functional expression as an amino acid transporter. The expression of this transporter is up-regulated in tumor cells and rapidly-growing cells to support their proliferation. Here, we studied the expression of LAT1 and 4F2hc in human cultured cells by real-time PCR and Western blot, and found that human brain astrocytomas, U343MGa, highly expressed LAT1 and 4F2hc mRNAs and proteins. The uptake of [14C]leucine by U343MGa cells is Na+-independent and inhibited by BCH (2-amino-2-norbornane carboxylic acid), and branched and aromatic amino acids, indicating that the LAT1 is expressed at the cell surface. Pulse chase labeling and surface labeling experiments of this cell line indicate that the protein synthesis of LAT1 and 4F2hc is slow, however, the heterodimeric complex assembled in the cells is very stable, and that the disulfide bond between the LAT1 and 4F2hc is not directly involved in the stability of the heterodimer.
Asano
Shinji
S
Department of Molecular Physiology, College of Information Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan. ashinji@is.ritsumei.ac.jp
Kameyama
Megumi
M
Oura
Ayako
A
Morisato
Anna
A
Sakai
Hideki
H
Tabuchi
Yoshiaki
Y
Chairoungdua
Arthit
A
Endou
Hitoshi
H
Kanai
Yoshikatsu
Y
D000596:Amino Acids / Q000494:pharmacology; D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002250:Carbon Radioisotopes; D002460:Cell Line; D045744:Cell Line, Tumor; D004591:Electrophoresis, Polyacrylamide Gel; D027282:Fusion Regulatory Protein 1, Heavy Chain / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D019073:HT29 Cells; D006367:HeLa Cells; D006801:Humans; D027283:Large Neutral Amino Acid-Transporter 1 / Q000235:genetics* / Q000378:metabolism; D007930:Leucine / Q000378:metabolism / Q000493:pharmacokinetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000235:genetics
D000596:Amino Acids; D002250:Carbon Radioisotopes; D027282:Fusion Regulatory Protein 1, Heavy Chain; D027283:Large Neutral Amino Acid-Transporter 1; D012333:RNA, Messenger; D007930:Leucine