Protein of the ribosome, large ribonucleoprotein particles where the translation of messenger RNA (mRNA) into protein occurs. They are both free in the cytoplasm and attached to membranes of eukaryotic and prokaryotic cells. Ribosomes are also present in all plastids and mitochondria, where they translate organelle-encoded mRNA.

A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.