Amino acid sequence of the biosynthetic precursor to a human hormone

The radiosequencing method used to determine the structure of precursors of hormones and other secretory proteins was reviewed. Determination of the primary structure of the hydrophobic Xp of the biosynthetic precursor to hPL was described. This is the first human hormone whose precursor structure has been determined completely by this method. Comparison of the sequence we determined with the sequence of rat pre-growth hormone deduced from the structure of its coding DNA revealed striking homology of the Xp regions. These findings support coevolutionary development of the DNA for both the Xp segment and mature protein regions of these related hormones.