Stimulation of proinsulin biosynthesis by purine-ribonucleosides and D-ribose.
Inosine and guanosine were potent stimuli of proinsulin biosynthesis ([3H]leucine incorporation) in isolated pancreatic islets of the rat. The effect was nearly abolished by formycin B, an inhibitor of purine nucleoside phosphorylase, but not by D-mannoheptulose. The corresponding bases had no effect on the rate of proinsulin biosynthesis. D-ribose enhance proinsulin biosynthesis at low concentrations )0.3-0.6mM) but concentrations above 5 mM were ineffective. The effect of all three compounds was highly specific for proinsulin biosynthesis, since incorporation of [3H]leucine into other islet proteins was not significantly stimulated. The data strongly indicate that metabolic signals regulate modulation of proinsulin biosynthesis in the beta cells.
D000818:Animals; D005573:Formycins / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D006151:Guanosine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007288:Inosine / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008356:Mannoheptulose / Q000494:pharmacology; D011384:Proinsulin / Q000096:biosynthesis*; D051381:Rats; D012263:Ribonucleosides / Q000494:pharmacology; D012266:Ribose / Q000494:pharmacology*; D013268:Stimulation, Chemical
D005573:Formycins; D012263:Ribonucleosides; D006151:Guanosine; D007288:Inosine; D008356:Mannoheptulose; D012266:Ribose; D011384:Proinsulin; D005947:Glucose