Intracellular compartmentation and secretion of carp proinsulin synthesized in Xenopus oocytes.

Carp proinsulin and rabbit globin, synthesized in Xenopus oocytes in response to simultaneously injected mRNAs, are found in membrane vesicles and in the cytosol respectively. After 24 h of incubation labeled proinsulin, but not globin, is found also in the medium, indicating specific secretion from the oocytes. No insulin could be found either within or outside the oocytes. The results provide further evidence that the mRNA for a given protein contains the information for its intracellular destination and its eventual secretion.