Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleotide sequence of avian (chicken) prepro-PTH (prepro-PTH) mRNA was determined from a 2.3-kilobase fragment of complementary chicken parathyroid DNA cloned in E. coli MM 924. Northern blot analysis of chicken parathyroid mRNA, using both bovine and chicken cDNA probes, showed that the mRNA (2.3 kilobases) for chicken hormone precursor was approximately 3 times the size of mRNA for mammalian prepro-PTH. Cleavage of the cloned DNA with restriction endonuclease Pstl resulted in three fragments, each of which was subjected to sequence determination. The hormone sequence deduced from the DNA showed that chicken prepro-PTH mRNA encoded a 119-amino acid precursor which included a 25-amino acid signal sequence, a six-residue prohormone peptide, and an 88-amino acid hormone. The hormonal peptide was four residues longer than all known mammalian homologs and included gene deletions and insertions. There was significant homology of sequence in the biologically active 1-34 region with mammalian hormones, but much less in the middle and carboxyl-terminal regions. This is the first nonmammalian PTH sequence to be determined and should prove useful in studying evolution of the gene as well as structure-function relationships of the hormone.
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PMID:Nucleotide sequence of the DNA complementary to avian (chicken) preproparathyroid hormone mRNA and the deduced sequence of the hormone precursor. 271 Jan 35

PTH-like peptides and messenger RNA (mRNA) have recently been detected in neural tissues, but it is uncertain whether this reflects the transcription of the PTH gene or that of a closely related gene. This possibility has, therefore, been investigated. PTH-like complementary DNA (cDNA) moieties of predicted size were readily generated from reverse transcribed brain (hypothalamic and extrahypothalamic tissue) and pituitary RNA, using polymerase chain reaction (PCR) with three sets of overlapping oligonucleotide primers designed to amplify PTH cDNA fragments of 285, 372, and 459 base pairs (bp). PCR reamplification of the largest hypothalamic moiety with an internal set of primers also generated a cDNA fragment of the predicted size (372 bp). Restriction endonuclease digestion with BstNI cleaved the largest hypothalamic cDNA moieties into smaller fragments of 217 and 242 bp, identical to the cleavage of parathyroidal PTH cDNA. Rapid amplification of cDNA ends of the 3'-flanking cDNA sequences also produced hypothalamic and extra-hypothalamic cDNA moieties identical in size (499 bp) to parathyroidal PTH cDNA. Southern analysis of these PCR and rapid amplification of cDNA end cDNA fragments further indicated homology with PTH cDNA. This homology was subsequently confirmed by nucleotide sequencing, which demonstrated complete homology between the neural and parathyroidal cDNA fragments. This homology extended over 673 bp (spanning nucleotides 31-709 of PTH cDNA), encompassing 95% of the entire parathyroidal PTH cDNA. The mRNA for this gene, determined by Northern blotting with a riboprobe for PTH mRNA, was of identical size to the parathyroidal PTH, but its abundance in brain was less than 0.01% of that expressed in the parathyroid glands. This transcript was not, however, detected in liver. The translation of this moiety in hypothalamic tissues was indicated by the presence of a protein in the rat hypothalamus that was immunoreactive with PTH-(1-84) antiserum and of comparable size to that in parathyroidal tissue. The abundance of this protein in hypothalamic tissue was approximately 0.25% of that in the parathyroid glands, suggesting tissue-specific differences in its rate of synthesis, processing, or degradation. These results, therefore, demonstrate that the brain is an extraparathyroidal site of PTH gene expression and suggest autocrine or paracrine roles for PTH in neural function.
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PMID:Sequence analysis of hypothalamic parathyroid hormone messenger ribonucleic acid. 758 14