Vault cytoplasmic ribonucleoprotein

A Vault is a highly conserved cytoplasmic ribonucleoprotein found in eukaryotic cells. They are composed of four components; three proteins and an RNA molecule.

Despite being large (three times the size of ribosomes) and numerous (thousands of copies per cell), vaults were not discovered until 1986. Their presence was not detected until then because they are not stained by traditional electron microscopy stains. Little is currently known about their function.