The Signal Recognition Particle (SRP) mediates the co-translational targeting of proteins destined for the secretory pathway. The particle recognizes a signal peptide as it emerges from the ribosome, temporarily halts translation and mediates docking of the SRP-ribosome-nascent chain complex to a membrane-bound receptor. SRP consists of 7SL RNA and six proteins. The ribonucleoprotein can be divided into two functional domains, the Alu domain and S domain.

The last decade has yielded a significant amount of structural data on both of the SRP domains. However, dynamic information on the assembly and function of the SRP is lacking. We are studying the folding dynamics and SRP assembly using different single-molecule FRET techniques.