Cell-Free Biosynthesis of Somatostatin Precursors: Evidence for Multiple Forms of Preprosomatostatin

It has been demonstrated [Shields, D. (1980) J. Biol. Chem. 255, 11625-11628] that mRNA isolated from the islets of Langerhans codes for two preprosomatostatin molecules of apparent molecular weights 18,000 and 19,000, respectively. Here evidence is presented that in vitro translation of pancreatic...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1982-06, Vol.79 (12), p.3729-3733
Main Authors: Warren, Thomas G., Shields, Dennis
Format: Article
Language:English
Subjects:
Amino acids
Animals
Antibodies
Antiserum
Cell free system
Electrophoresis
Fishes
Gels
Genetic Variation
Islets of Langerhans
Islets of Langerhans - metabolism
Isoelectric Point
Lophius americanus
Messenger RNA
Molecular Weight
Molecules
Protein Precursors - biosynthesis
Protein Precursors - genetics
RNA, Messenger - genetics
Somatostatin - analogs & derivatives
Somatostatin - biosynthesis
Somatostatin - genetics
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Summary:It has been demonstrated [Shields, D. (1980) J. Biol. Chem. 255, 11625-11628] that mRNA isolated from the islets of Langerhans codes for two preprosomatostatin molecules of apparent molecular weights 18,000 and 19,000, respectively. Here evidence is presented that in vitro translation of pancreatic islet mRNA in two different cell-free protein-synthesizing systems directs the synthesis of up to nine distinct forms of somatostatin-immunoreactive polypeptides. The multiplicity of the preprosomatostatin molecules was the result of initiation of translation from separate species of mRNA as demonstrated by amino-terminal labeling with N-formyl-[35S]Met-tRNAf Met. Translation of islet mRNA isolated from different individual animals showed that all of the preprosomatostatin polypeptides were present amongst the cell-free products, which implies that the multiple forms were not due to genetic variation in the wild population. Based on their apparent molecular weights and distinctly different isoelectric points, the different preprosomatostatin molecules could be classified into two major families. These results suggest that the anglerfish preprosomatostatins are encoded by separate mRNA species and are consistent with the existence of a multigene family for somatostatin.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.79.12.3729