InterPro domain: IPR034652

Signal recognition particles (SRPs) are ribonucleoprotein complexes that target particular nascent pre-secretory proteins to the endoplasmic reticulum. SRP68 is one of the two largest proteins found in SRPs (the other being SRP72), and it forms a heterodimer with SRP72. Heterodimer formation is essential for SRP function [ 1 ]. SRP68 binds to SRP RNA directly, while SRP72 binds the SRP RNA largely via non-specific electrostatic interaction. The binding of SRP72 with SRP RNA enhances the affinity of SRP68 for the RNA. This entry describes the N-terminal RNA-binding domain (RBD) of SRP68, a tetratricopeptide-like module. Interactions between SRP68-RBD and SRP RNA (7SL RNA) are thought to facilitate a conformation of SRP RNA that is required for interactions with ribosomal RNA [ 2 , 3 , 4 ].

1. Characterization of the SRP68/72 interface of human signal recognition particle by systematic site-directed mutagenesis. Protein Sci. 18, 2183-95
2. SRP RNA remodeling by SRP68 explains its role in protein translocation. Science 344, 101-4
3. Protein SRP68 of human signal recognition particle: identification of the RNA and SRP72 binding domains. Protein Sci. 15, 1290-302
4. Structures of human SRP72 complexes provide insights into SRP RNA remodeling and ribosome interaction. Nucleic Acids Res 45, 470-481