GTPase involved in protein precursor import into chloroplasts. Seems to recognize chloroplast-destined precursor proteins and regulate their presentation to the translocation channel through GTP hydrolysis (By similarity). Functions as an essential component of the outer chloroplast membrane translocon (TOC) complex, which, in turn, catalyzes the import of nucleus-encoded precursor polypeptides from the cytoplasm to the chloroplast (PubMed:23167510). Binds 1 Mg(2+) ion by subunit. Homodimer, heterodimer with other TOC proteins, and monomer. Part of the TOC core complex that includes 1 protein for the specific recognition of transit peptides surrounded by a ring composed of four proteins forming translocation channels, and four to five GTP-binding proteins providing energy. This core complex can interact with components of the TIC complex to form a larger import complex (By similarity). Interacts with ARSA1 (PubMed:28382961). Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. AIG1/Toc34/Toc159-like paraseptin GTPase family. TOC34 subfamily.