The function of SRP54 (signal recognition particle 54, Ensembl gene identifier ENSG00000100883) is as follows. 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) (PubMed:34020957). As part of the SRP complex, associates with the SRP receptor (SR) component SRPRA to target secretory proteins to the endoplasmic reticulum membrane (PubMed:34020957). Binds to the signal sequence of presecretory proteins when they emerge from the ribosomes (PubMed:34020957). Displays basal GTPase activity, and stimulates reciprocal GTPase activation of the SR subunit SRPRA (PubMed:28972538, PubMed:34020957). Forms a guanosine 5'-triphosphate (GTP)-dependent complex with the SR subunit SRPRA (PubMed:34020957). SR compaction and GTPase mediated rearrangement of SR drive SRP-mediated cotranslational protein translocation into the ER (PubMed:34020957). 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 (PubMed:28972538, PubMed:29914977). {ECO:0000250|UniProtKB:P61010, ECO:0000269|PubMed:28972538, ECO:0000269|PubMed:29914977, ECO:0000269|PubMed:34020957}.