Expression cloning of a mammalian amino acid transporter or modifier by complementation of a yeast transport mutant.
A cDNA clone named L21 was isolated from L6 rat muscle cells by complementation of a yeast proline transport mutant. L21 cDNA has 2,268 bp and codes for a peptide of 228 amino acids with four potential transmembrane domains. The amino acid sequence of L21 shows no homology to any known proteins. Expression of L21 cDNA enables the mutant yeast to grow in proline as the sole nitrogen source and to transport proline, alpha-aminoisobutyric acid (AIB) and leucine. The Km for proline is about 1.0 mM. The substrate specificity of L21 expressed in yeast shows no striking similarity to known mammalian amino acid transporters.
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Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
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Johnstone
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D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015723:Gene Library; D005816:Genetic Complementation Test; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008297:Male; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D011392:Proline / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development*; D014158:Transcription, Genetic
D026905:Amino Acid Transport Systems; D000621:Aminoisobutyric Acids; D002352:Carrier Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; C100049:2-aminoisobutyric acid; D011392:Proline; D007930:Leucine