On the protein composition of ribonucleoprotein particles before and after fertilization fo sea urchin eggs (Echinus esculentus).

Experiments indicate that eggs and embryos of the North Sea sea urchin Echinus esculentus are excellent material to investigate the regulation of protein synthesis before and after fertilization. The dormant egg contains several proteins which are absent from embryos. Such additional proteins have been detected on the small ribosomal subunits, in the salt wash of whole ribosomes, and associated with cytoplasmic messenger ribonucleoprotein particles.