Dynamics of co-translational protein targeting

Most membrane and secretory proteins are delivered co-translationally to protein translocation channels in their destination membrane by the signal recognition particle (SAP) and its receptor. This co-translational molecular machinery is conserved across all kingdoms of life, though it varies in composition and function. Here we report recent progress towards understanding the mechanism of SAP function, focusing on findings about Escherichia coli SRP's conformational dynamics throughout the targeting process. These insights shed light on a key checkpoint in the targeting cycle: how SAP regulates engagement of an actively translating ribosome with the translocation machinery at the membrane.