Subunit composition of Eukaryotic & Prokaryotic ribosomes
Ribosome
subunits comprise one or two rRNA molecules, plus a
variable number of proteins.
Combinations of rRNAs and
proteins
typically have a smaller sedimentation rate (S) than their
component parts, due to condensation. In eukaryotes,
the complete 80S monosome
comprises a 40S Small Subunit
(SSU)
that includes the 18S rRNA,
and a 60S Large Subunit
(LSU)
that includes the 28S, 5.8S, and 5S rRNAs. Prokaryotic ribosomes
are somewhat smaller, but include analogous subunits.