Binds to the signal sequence of presecretory protein when they emerge from the ribosomes and transfers them to TRAM (translocating chain-associating membrane protein) (By similarity). Plays a role in proliferation of granulocytic cells, neutrophils migration capacity and exocrine pancreas development (PubMed:28972538). GTP + H2O = GDP + H(+) + phosphate Signal recognition particle consists of a 7S RNA molecule and at least six protein subunits. At 26 hours post fertilization (hpf), expression is ubiquitous (PubMed:28972538). Later in development, expression is more pronounced in the anterior part (PubMed:28972538). Has a two domain structure: the G-domain binds GTP; the M-domain binds the 7S RNA in presence of SRP19 and also binds the signal sequence. Mutants show profound reductions in neutrophil counts and chemotaxis as well as a diminished exocrine pancreas size. Belongs to the GTP-binding SRP family. SRP54 subfamily.