SEQUENCE OF AN ACIDIC RIBOSOMAL-PROTEIN FROM THE JELLYFISH POLYORCHIS-PENICILLATUS

We have isolated a cDNA clone from the jellyfish Polyorchis penicillatus that encodes the homologue of the A1 acidic ribosomal protein previously characterized in human, brine shrimp, fruit fly, and yeast. The sequence of this protein is strongly conserved among the five eukaryotic species for which it has been determined. Conservation is greatest in the amino-terminal 51 amino acids and the carboxyl-terminal 25 amino acids. This suggests that these regions are necessary for interactions with other components of the protein synthetic machinery, while the central part of the protein has a less specific role to play. Comparison of the sequences obtained from the different species indicate that the metazoan lineages all appear to have arisen at approximately the same time and significantly later than the time of divergence of yeast from the common ancestor of the Metazoa.