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. Probably specialized in the import of nuclear encoded non-photosynthetic preproteins from the cytoplasm to the chloroplast. Binds 1 Mg(2+) ion by subunit. Homodimer, heterodimer with TOC33, 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. Chloroplastic protein precursor such as prSS (precursor of the RuBisCO small subunit) interacts with these complexes. The TOC complex contains a specific subset of polar lipids such as digalactosyldiacylglyceride (DGDG), phosphatidylcholine (PC) and phosphatidylglycerol (PG). Interacts at least with TOC75. Interacts with AKR2A and AKR2B (PubMed:20215589). May contain beta barrel transmembrane regions. Mostly expressed in roots and flowers, and, to a lower extent, in seedlings, stems, and leaves. Expressed at a relatively uniform, low level at most stages of development. Observed in cotyledons and hypocotyls of young seedling. Expressed in apical meristems. Found in the whole roots. Expressed in middle-aged leaves. In flowers, mostly localized in meristems, but is also present in all organs. Induced in light but repressed in darkness. Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. AIG1/Toc34/Toc159-like paraseptin GTPase family. TOC34 subfamily.