SRP72 is a core component of the signal recognition particle ribonucleoprotein complex that functions in targeting nascent secretory proteins to the endoplasmic reticulum membrane [, ]. SRP72 binds the 7S RNA only in presence of SRP68 [].
The signal recognition particle (SRP) is a multimeric protein, which along with its conjugate receptor (SR), is involved in targeting secretory proteins to the rough endoplasmic reticulum (RER) membrane in eukaryotes, or to the plasma membrane in prokaryotes [, ]. SRP recognises the signal sequence of the nascent polypeptide on the ribosome. In eukaryotes this retards its elongation until SRP docks the ribosome-polypeptide complex to the RER membrane via the SR receptor []. Eukaryotic SRP consists of six polypeptides (SRP9, SRP14, SRP19, SRP54, SRP68 and SRP72) and a single 300 nucleotide 7S RNA molecule. The RNA component catalyses the interaction of SRP with its SR receptor []. In higher eukaryotes, the SRP complex consists of the Alu domain and the S domain linked by the SRP RNA. The Alu domain consists of a heterodimer of SRP9 and SRP14 bound to the 5' and 3' terminal sequences of SRP RNA. This domain is necessary for retarding the elongation of the nascent polypeptide chain, which gives SRP time to dock the ribosome-polypeptide complex to the RER membrane. In archaea, the SRP complex contains 7S RNA like its eukaryotic counterpart, yet only includes two of the six protein subunits found in the eukarytic complex: SRP19 and SRP54 [].This entry represents the RNA binding domain of the SRP72 subunit. This domain is responsible for the binding of SRP72 to the 7S SRP RNA [].
The signal recognition particle (SRP) is a large ribonucleoprotein complex that targets secretory and membrane proteins to the endoplasmic reticulum membrane [, ]. The mammalian SRP contains a 303-nucleotide SRP RNA and six proteins, named SRP9, SRP14, SRP19, SRP54, SRP68, and SRP72. Among them, the two largest, SRP68 and SRP72, form a stable SRP68/72 heterodimer of unknown structure, which is required for sorting secretory proteins []. 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.
Signal recognition particles (SRPs) are ribonucleoprotein complexes that target particular nascent pre-secretory proteins to the endoplasmic reticulum. The SRP complex targets the ribosome-nascent chain complex to the SRP receptor (SR), which is anchored in the ER, where SR compaction and GTPase rearrangement drive cotranslational protein translocation into the ER []. 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 []. SRP68 binds to SRP RNA directly, while SRP72 binds the SRP RNA largely via nonspecific 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 [, , ].
Signal recognition particles (SRPs) are ribonucleoprotein complexes that target particular nascent pre-secretory proteins to the endoplasmic reticulum. The SRP complex targets the ribosome-nascent chain complex to the SRP receptor (SR), which is anchored in the ER, where SR compaction and GTPase rearrangement drive cotranslational protein translocation into the ER []. 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 []. SRP68 binds to SRP RNA directly, while SRP72 binds the SRP RNA largely via nonspecific 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 [, , ].
