The number and size of the proteins in the subunits of human placental ribosomes

Abstract

Several reports were recently published on the number and size of the proteins from eukaryotic ribosomes, isolated mostly from various organs of rodents or Xenopus Iaevis [l-l 21 . However, since little structural work has been done on human ribosomes, we report here on the number and size distribution of the proteins from both subunits of human placental ribosomes. Using an improved two-dimensional (2-D) acrylamide gel electrophoresis system, thirty-six cationically moving proteins with molecular weights ranging from 8 900 to 61 900 were found in the large subunit and twenty-eight with molecular weights between 9 600 and 37 600 in the small subunit. Moreover, two proteins, moving anionically at pH 8.6 and which stained very weakly, can be demonstrated in the protein mixture from undissociated ribosomes. They presumably belong to the small subunit.