Signal recognition particle 54 kDa protein

Component of the signal recognition particle (SRP) complex, a ribonucleoprotein complex that mediates the cotranslational targeting of secretory and membrane proteins to the endoplasmic reticulum (ER). As part of the SRP complex, associates with the SRP receptor (SR) component SRPRA to target secretory proteins to the endoplasmic reticulum membrane. Binds to the signal sequence of presecretory proteins when they emerge from the ribosomes. Displays basal GTPase activity, and stimulates reciprocal GTPase activation of the SR subunit SRPRA. Forms a guanosine 5'-triphosphate (GTP)-dependent complex with the SR subunit SRPRA. SR compaction and GTPase mediated rearrangement of SR drive SRP-mediated cotranslational protein translocation into the ER. Requires the presence of SRP9/SRP14 and/or SRP19 to stably interact with RNA (By similarity). Plays a role in proliferation and differentiation of granulocytic cells, neutrophils migration capacity and exocrine pancreas development.