GTP-binding protein involved in membrane biogenesis and protein synthesis in chloroplast. Functions in the biogenesis of thylakoid membrane and plastid ribosome during chloroplast development. May be involved in the vesicular traffic between the chloroplast inner envelope membrane and thylakoids. Possesses GTPase activity in vitro. Exhibits a punctate staining pattern. Specifically expressed in leaves. Embryonic lethality when homozygous. Embryo maturation arrested at the late globular stage. Belongs to the TRAFAC class OBG-HflX-like GTPase superfamily. OBG GTPase family.