On the functions of the endoplasmic reticulum

Abstract

Ribonucleoprotein (RNP) particles were purified in a highly active state from a number of tissues of the rat. Particle yield varied considerably for different tissues but the composition of particles was fairly similar. From the early blastula stage of Psammechinus eggs active particles were also obtained, and at a higher yield than from preceding stages of development. Mitochondria also yielded protein synthesizing particles in a study of other cell components. No significant amino acid incorporation was obtained with purified RNP particles when they were used alone. Mechanisms of amino acid incorporation are discussed. Experiments show the possibility of a functional inter-relationship between endoplasmic particles and membranes.