The signal recognition particle (SRP) and its receptor compose a universally
conserved and essential cellular machinery that couples the synthesis
of nascent proteins to their proper membrane localization. The
past decade has witnessed an explosion in in-depth mechanistic investigations
of this targeting machine at increasingly higher resolutions. In
this review, we summarize recent work that elucidates how the SRP and
SRP receptor interact with the cargo protein and the target membrane,
respectively, and how these interactions are coupled to a novel GTPase
cycle in the SRP·SRP receptor complex to provide the driving force
and enhance the fidelity of this fundamental cellular pathway. We also
discuss emerging frontiers in which important questions remain to be
addressed
