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) (By similarity). Binds directly to 7SL RNA (By similarity). Mediates binding of SRP54 to the SRP complex (By similarity). . This is the function of ENSG00000153037 (SRP19, signal recognition particle 19).