Nascent secretory or membrane proteins contain an amino-terminal signal peptide that mediates their targeting to the plasma membrane (in prokaryotes) or endoplasmic reticulum (in eukaryotes). This peptide is recognized by the signal recognition particle (SRP). A universally conserved component of the SRP is known as SRP54 (Ffh in bacteria). Here, the crystal structure of Sulfolobus solfataricus SRP54 fused to a signal peptide is presented, revealing how the signal peptide is recognized by SRP54.
Recognition of a signal peptide by the signal recognition particle