Bovine arylalkylamine N-acetyltransferase activity correlated with mRNA expression in pineal and retina.
Arylalkylamine N-acetyltransferase (AA-NAT, E. C. 2.3.1.87) is the enzyme that catalyzes the transfer of an acetyl group from acetyl-CoA to serotonin to form N-acetylserotonin (NAS) in the indoleamine biosynthetic pathway. Bovine pineal AA-NAT, partially purified on an anion exchange column, displayed an 8-fold higher enzymatic activity in pineals from animals killed in early morning (0800) compared to an afternoon group (1430). Poly A(+) mRNA was isolated from early morning bovine pineals, used to construct a mammalian expression cDNA library (lambdaZAP Express), and then screened with a rat AA-NAT cDNA to isolate a 924 basepair cDNA that encodes the bovine pineal AA-NAT. The amino acid sequence alignment reveals that bovine AA-NAT shares 94.20%, 78.54%, 76.33% and 56.3% identity to ovine, rat, human and chicken sequences, respectively. Northern blot analysis demonstrates a 0.7-fold higher mRNA level in pineal glands taken from animals from the 0800 time-point compared with mRNA from the 1430 time-point. AA-NAT mRNA was expressed at high levels in pineal and retina, but the message was undetectable in adrenal, cerebellum, cortex, small intestine, testis and thyroid. Based on the significant identity of amino acid sequence and the similar mRNA expression pattern, these data suggest that the bovine AA-NAT is more analogous to the ovine rather than either the rat, human or chicken AA-NAT.
Mary D. Allen Laboratory for Vision Research, Doheny Eye Institute, Department of Cell and Neurobiology, University of Southern California School of Medicine, 1333 San Pablo Street, BMT 401, Los Angeles, CA 90033, USA. ccraft@hsc.usc.edu
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D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D002417:Cattle; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D008550:Melatonin / Q000378:metabolism; D008969:Molecular Sequence Data; D010870:Pineal Gland / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D012701:Serotonin / Q000378:metabolism; D013379:Substrate Specificity
D018076:DNA, Complementary; D012333:RNA, Messenger; D012701:Serotonin; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin