Abstract
Fluorescence histochemistry has demonstrated an abundance of tyrosine and arginine residues in the growth hormone (GH) producing cells of the pituitary of several mammals. Granules from pig pituitaries were purified by passage through a succession of Millipore filters followed by centrifugation on a continuous sucrose gradient. One granular fraction, rich in GH, was found to contain proteins or peptides rich in tyrosine and arginine. Gel chromatography of the acid-soluble components from sedimented pituitary granules revealed that the arginine- and tyrosine-rich material was heterogeneous. The arginine-containing peptides and proteins could be separated into several peaks with molecular weights from 5000-10,000 and higher. The tyrosine-containing material comprised one peptide with a molecular weight of 5000-10,000 and another much smaller peptide. Since GH itself is not excessively rich in either tyrosine or arginine, the tyrosine- and arginine-containing proteins or peptides probably constitute as yet unidentified granular components, distinct from GH itself.