Exhibits GTPase activity which converts GTP ligands to GDP (PubMed:29769312). Component of the plastid division machinery consisting in a binary fission accomplished by the simultaneous constriction of the FtsZ ring on the stromal side of the inner envelope membrane, and the ARC5 ring on the cytosolic side of the outer envelope membrane (PubMed:25731613). Required for plastid division in a dose-dependent manner. In the vegetative shoot apex, at the shoot apical meristem (SAM), where the proplastid-to-chloroplast transition takes place, major contributor of plastid division in the L1 and L3 layers and contributes equally with FTSZ1 in the L2 layer (PubMed:29920253). GTPase activity is enhanced by ARC3. Aggregates to form a contractile ring-like structure; contraction of the ring was accompanied by an increase in the filament turnover rate (PubMed:29769312, PubMed:27322658). Self-interacts and binds to FTSZ1 in heteromers to form two morphologically distinct types of filaments, termed type-I (smooth filaments) and -II (rough filaments), in a GTP-dependent manner; the GDP-induced disassembly is inhibited by ARC6 (PubMed:29769312, PubMed:27322658). Interacts (via C-terminus) with ARC6; this interaction enables ARC3 binding to FTSZ2 (PubMed:29967285, PubMed:29769312, PubMed:29138260). Part of a complex made of ARC3, ARC6, FTSZ1 and FTSZ2 (PubMed:22823492). Binds to MCD1 in an ARC6-dependent manner (PubMed:29967285). Binds to CDP1/PARC6 (PubMed:26527658, PubMed:28984364). Part of a complex made of CDP1/PARC6, ARC3 and FtsZ proteins in the middle of the plastid; this complex enhances the dynamics of Z rings during chloroplast division (PubMed:30824505). Binds to PGK1 (PubMed:22823492). Forms a contractile ring at the chloroplast midpoint that coaligns with FTSZ1 rings (PubMed:18431481, PubMed:29769312, PubMed:22823492, PubMed:25731613). Exhibits a dynamic trunover in FtsZ ring facilitated by ARC3-mediated destabilization (PubMed:25731613). Slightly induced by gibberellic acid (GA). Filaments containing FTSZ2-1 are stabilized when in complex with GTP but destabilized after conversion of GTP into GDP; ARC6 conteracts this destabilisation by preventing the dissociation of GDP-bound FTSZ2 molecules thus inhibiting filament disassembly whereas ARC3 promotes GTPase activity thus accelerating the conversion of GTP into GDP and triggering FtsZ2 filaments disassembly. Phosphorylation at Ser-143 is necessary for interactions with ARC3, ARC6, FTSZ1 and FTSZ2-2. Phosphorylations at Ser-143 and Thr-286 are required for the formation of contractile ring at the chloroplast midpoint. Reduced number of heterogeneous large chloroplast population (small and large plastids) due to impaired plastid division (PubMed:25731613). Increased plastid volume in young leaf primordia and in the shoot apical meristem (SAM), including the central zone as well as peripheral zone of L1, the outermost layer, the peripheral zone of L2, and the peripheral zone of L3 (PubMed:29920253). Belongs to the FtsZ family.