Component of the plastid division machinery required for PDV1 localization to constriction sites. Involved in chloroplast division site placement (PubMed:28984364, PubMed:23936263). Required for the proper formation of FtsZ rings at the division site in nongreen plastids (e.g. etioplasts) (PubMed:23936263). Inhibits FtsZ assembly, functioning as an antagonistic regulator of FtsZ dynamics against ARC6, by recruiting ARC3 to the middle of the plastid to facilitates its interaction with FtsZ proteins (PubMed:26527658, PubMed:30824505). Required during stromule biogenesis in the leaf epidermis, especially in non-mesophyll cells plastids (PubMed:28984364). Self-interacts (PubMed:19564892, PubMed:28984364). Interacts (via N-terminus) with ARC3 (via MORN domains) (PubMed:19453460, PubMed:19564892, PubMed:26527658). Binds (via N-terminus) to FTSZ2 proteins, FTSZ2-1 and FTSZ2-2 (PubMed:26527658, PubMed:28984364, PubMed:30824505). Recruited ARC3 to the middle of the plastid where subsequent complex made of CDP1/PARC6, ARC3 and FtsZ proteins can form; this complex enhances the dynamics of Z rings during chloroplast division (PubMed:30824505). Interacts (via C-terminus) with PDV1 (via C-terminus) (PubMed:26527658). Interacts with MIND1 (PubMed:28984364). Localizes both to the mid-plastid and to a single spot at one pole. Exclusively expressed in young green tissues such as young cotyledons, shoot apex, emerging leaves and budding inflorescence. Defects of chloroplast and FtsZ filament morphology (e.g. long FtsZ filaments formed by multiple rings or spirals); elongated chloroplasts with multiple division sites (PubMed:19453460, PubMed:19564892, PubMed:23936263). Aberrant stromule biogenesis in the leaf epidermis associated with giant and pleomorphic amoeboid chloroplasts, typically having one or more constrictions as well as one or more extremely long stromules (PubMed:28984364). Reduced number of enlarged etioplasts in cotyledons associated with the formation of multiple FtsZ-rings (PubMed:23936263).