A
ribosomal protein is any of the
proteins that, in conjunction with
rRNA, make up the
ribosomal subunits involved in the cellular process of
translation. A large part of the knowledge about these organic molecules has come from the study of
E. coli ribosomes. All ribosomal proteins have been isolated and many specific antibodies have been produced. These, together with
electronic microscopy and the use of certain reactives, have allowed for the determination of the topography of the proteins in the ribosome. E.coli, other
bacteria and
Archaea have a 30S small subunit and a 50S large subunit, whereas humans and
yeasts have a 40S small subunit and a 60S large subunit. Equivalent subunits are frequently numbered differently between bacteria, Archaea, yeasts and humans. More recently, a near-complete (near)atomic picture of the ribosomal proteins is emerging from the latest high-resolution cryo-EM data (including PDB ID: 5AFI).