The In Vivo Uptake and Incorporation of Radioisotopes into Proteins of Wheat Endosperm

Abstract

A procedure is described for the quantitative i'301ation of the protein bodies from developing wheat endosperm. The changes with time in specific a.ctivity of the storage proteins (present in the protein bodies) and of the soluble proteins (present in the high-speed supernatant fraction) have been followed in "pulse"labelling experiments. Excised wheat heads were exposed to [35SJsulphate for periods of 5 min to 1 hr; dilution of the 35S-radioactivity within the wheat head before the incorporation of radioactivity into the endosperm proteins resulted in a constant ratio of the specific activity of the soluble proteins to that of the storage proteinfl.