Molecular cloning and nucleotide sequence of a cDNA encoding hydroxyindole O-methyltransferase from chicken pineal gland.
Hydroxyindole O-methyltransferase (EC 2.1.1.4) is the enzyme that catalyses the synthesis of melatonin in the pineal gland and in the retina. Polyadenylated RNA from chicken pineal glands was used to prepare a cDNA library in lambda gt11. The library was screened with an antiserum directed against chicken hydroxyindole O-methyltransferase, and one cDNA clone was isolated. The fusion protein expressed by phage lysogens was identified on Western blots as a 165 kDA immunoreactive protein (beta-galactosidase, 110 kDa; hydroxyindole O-methyltransferase, 38 kDa). The fusion protein exhibited hydroxyindole O-methyltransferase activity. Its Km values for N-acetyl-5-hydroxytryptamine and S-adenosylmethionine were 5 times those of the natural enzyme. The intrinsic activity of the fusion protein was approx. 0.25% that of the natural enzyme. The cDNA consisted of 1436 nucleotides, including a 1038-nucleotide sequence encoding a full-length 346-amino-acid hydroxyindole O-methyltransferase. Comparison with bovine hydroxyindole O-methyltransferase [Ishida, Obinata & Deguchi (1987) J. Biol. Chem. 262, 2895-2899] revealed 52% identity in nucleotide sequences and 44% identity in peptide sequences. Northern-blot analysis revealed the presence of hydroxyindole O-methyltransferase mRNA transcripts in chicken pineal gland and retina, but not in the telencephalon.
Laboratoire de Neurobiologie et Neuroendocrinologie Cellulaires, URA CNRS N. 290.
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P
Voisin
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Guerlotté
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M
Bernard
J P
JP
Collin
M
M
Cogné
D000121:Acetylserotonin O-Methyltransferase / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002645:Chickens; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D008969:Molecular Sequence Data; D010870:Pineal Gland / Q000201:enzymology*; D012313:RNA / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics; D015183:Restriction Mapping; D012160:Retina / Q000201:enzymology
D011993:Recombinant Fusion Proteins; D012313:RNA; D004247:DNA; D000121:Acetylserotonin O-Methyltransferase