Cell-free synthesis of fish preproinsulin, and processing by heterologous mammalian microsomal membranes.

Publisher Website
Google Scholar
Abstract
Poly(A)-containing mRNA isolated from the islets of Langerhans obtained from 2 species of fish, angler fish (Lophius americanus) and sea raven (Hemitripterus americanus), stimulated protein synthesis 16-fold in a wheat germ cell-free system. Characterization of the translation products by polyacrylamide gel electrophoresis in sodium dodecylsulfate showed a major polypeptide weighing 11,500 daltons that was specifically precipitated by an antibody against angler fish insulin. Partial sequence analysis of the amino terminal revealed that this polypeptide is preproinsulin, in which the amino terminus of proinsulin is preceded by either 23 (angler fish) or 25 (sea raven) amino acid residues. Translation of fish islet mRNA in a wheat germ cell-free system in the presence of dog pancreas microsomal membranes led to the correct cleavage of the nascent preproinsulin, resulting in the synthesis of authentic fish proinsulin, as verified by partial sequence analysis. The synthesized fish proinsulin was segregated, presumably into the luminal space of the dog pancreas micorsomal vesicles, because it was resistant to proteolysis by added trypsin and chymotrypsin. The mechanisms and information for the transfer of secretory proteins across the microsomal membrane are probably highly conserved during evolution.

This publication has 13 references indexed in Scilit: