Intestinal pre-prosomatostatin. Identification of mRNA coding for a precursor by cell-free translations and hybridization with a cloned islet cDNA.
Somatostatin, a tetradecapeptide hormone, is produced in numerous organs including the hypothalamus, pancreatic islets, and the gastrointestinal tract. Recently we identified two separate biosynthetic precursors of somatostatin (Mr = 16,000 and 14,000) among the cell-free translation products encoded by mRNAs prepared from the islets of the anglerfish. The nucleotide sequence of a cloned cDNA encoding the larger of the two pre-prosomatostatins revealed the sequence of the tetradecapeptide somatostatin at the COOH terminus of a polypeptide of 119 amino acids. We now have prepared poly(A)RNA from the intestine of the anglerfish and by immunoprecipitation analyses find a single somatostatin-related translation product that co-migrates during electrophoresis on sodium dodecyl sulfate-polyacrylamide gels with the larger islet pre-prosomatostatin (Mr = 16,000). Analyses of the sizes of the intestinal and islet mRNAs by agarose gel electrophoresis and hybridization with 32P-labeled cDNA containing the coding sequence for the large islet pre-prosomatostatin showed that the complementary RNA in the intestine (600 bases) is 30 nucleotides smaller than that in the islet (620-630 bases). These observations indicate that a gene encoding somatostatin is expressed in the intestine and suggest that the intestinal mRNA is distinct from the two mRNAs encoding the islet somatostatins.
D000818:Animals; D003001:Cloning, Molecular; D004274:DNA, Recombinant / Q000378:metabolism*; D005399:Fishes; D007421:Intestine, Small / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000235:genetics
D004274:DNA, Recombinant; D011498:Protein Precursors; D012333:RNA, Messenger; D013004:Somatostatin