Cell-free translation of messenger RNA extracted from a human insulinoma

M. Alan Permutt, Rose Chyn, Marc Goldford, Irving Boime

Research output: Contribution to journalArticlepeer-review


Total nucleic acid has been extracted from a human pancreatic insulinoma. Purification of the messenger RNA (mRNA) fraction by oligo-dT cellulose chromatography yielded 200 μg poly(A)-rich mRNA. This mRNA produced a 2-fold stimulation of protein synthesis in a wheat germ cell-free system. Analysis of the translation products by gel filtration chromatography (Biogel P-30) revealed nothing smaller than an acid-alcohol-soluble protein larger than bovine proinsulin. In contrast, insulinoma slices incubated with labeled amino acids synthesized smaller proteins which comigrated with bovine proinsulin and insulin. [ H]Leucine-labeled cell-free proteins were electrophoresed on NaDodSC4-urea polyacrylamide slab gels. In the presence of insulinoma mRNA, discrete proteins of 25, 000 and 11, 500 mol wt were synthesized. The 11, 500 mol wt protein was specifically immunoprecipitated with antiinsulin serum. Thus, cell-free translation of human insulinoma mRNA yields an immunoreactive insulin larger than proinsulin, which is the same size as fish and rat preproinsulins recently described.

Original languageEnglish
Pages (from-to)897-901
Number of pages5
JournalJournal of Clinical Endocrinology and Metabolism
Issue number6
StatePublished - Jun 1978


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