Bacterial signal recognition particle RNA

The signal recognition particle (SRP) is a universally conserved RNA:protein (ribonucleoprotein) complex involved in the translation and targeting of proteins to the cell membranes. The RNA and protein components of this complex are highly conserved but do vary between the different kingdoms of life.

The eukaryotic SRP consists of a 300-nucleotide RNA (known as 7S) and six proteins known as SRPs 72, 68, 54, 19, 14, and 9. Archaeal SRP consists of a 7S RNA and homologues of the eukaryotic SRP19 and SRP54 proteins. In most bacteria, the SRP consists of a RNA molecule (4.5S) and the Ffh protein (a homologue of the eukaryotic SRP54 protein). Some Gram-positive bacteria (e.g. Bacillus subtilis) have a longer eukaryote-like SRP RNA that includes an Alu domain. The Signal Recognition Particle Database (SRPDB) provides compilations of SRP components, with phylogenetic data and structural illustrations.