In vitro mRNA-directed synthesis and processing of an immunologically identified precursor to tetradecapeptide somatostatin from bovine hypothalamus

mRNA isolated from bovine hypothalami was used to direct the in vitro synthesis of a precursor to the tetradecapeptide somatostatin. When a rabbit reticulocyte lysate translation system supplemented with [35S]cysteine was used, a protein of apparent molecular weight 15 500 was identified as preprosomatostatin by reaction with specific rabbit antibodies. Cotranslational addition of dog pancreas microsomal membranes yielded an unglycosylated pro form of 14 500 daltons, implying the removal of a short signal sequence.