Table 1.

Composition of eukaryotic and prokaryotic small and large ribosomal subunits.

Ribosome	Monosome sedimentation rate	Small subunit	Large subunit
Eukaryotic	80S	40S: 18S rRNA and 33 ribosomal proteins (mammals)	60S: 5S, 5.8S, and 28S (mammals) rRNAs and 47 ribosomal proteins (mammals)
Prokaryotic	70S	30S: 16S rRNA and 22 ribosomal proteins	50S: 5S and 23S rRNAs and 34 ribosomal proteins
Mitochondrial	55S	28S: 12S rRNA and 30 ribosomal proteins	39S: mitochondrially-encoded tRNA, 16S rRNA, and 52 ribosomal subunits