Cloning and sequence analysis of cDNA for the precursor of human growth hormone-releasing factor, somatocrinin.

Abstract

Molecular cloning has established the primary structures of 2 precursors of the human pancreas growth hormone-releasing factor (hpGRF-44), somatocrinin. Both polypeptides contain the sequence of hpGRF-44 flanked by basic processing sites. The precursors include a putative signal sequence and a carboxyl-terminal amidation signal for hpGRF-44. The 2 forms of mRNA code for pre-pro-GRF-107 and pre-pro-GRF-108. Pre-pro-GRF-108 differs from pre-pro-GRF-107 by the insertion of a serine in the carboxyl-terminal portion of the precursor. In vitro translation of tumor poly(A)+ RNA followed by immunoprecipitation with GRF-specific antiserum and gel electrophoresis showed the MW of preprosomatocrinin to be .apprx. 13,000, which is in good agreement with the MW deduced from the sequences of the cDNA clones.