 This occurs via the interaction and docking of SRP with its cognate SRP receptor that is located in close proximity to the translocon.In eukaryotes there are three domains between SRP and its receptor that function in guanosine triphosphate (GTP) binding and hydrolysis.These are located in two related subunits in the SRP receptor (SRα and SRβ) and the SRP protein SRP54 (known as Ffh in bacteria).