GTPase that plays an essential role in the late steps of ribosome biogenesis. KM for GTP in the low affinity site could not be measured, experiments performed in the absence of Mg(2+). Associates with the 50S ribosomal subunit. Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. EngA (Der) GTPase family.