Component of the plastid division machinery (PubMed:16998069). Required to mediate the dissociation of ARC5/DRP5B from plastid outer envelope membranes (OEMs) at the midplastid constriction site in the cytoplasm, thus triggering ARC5/DRP5B ring turnover at the chloroplast division site (PubMed:16998069, PubMed:32005784). Binding to phosphatidylinositol 4-phosphate (PI4P) modulates negatively chloroplast division (PubMed:25736058). Interacts (via C-terminus) with CDP1/PARC6 (via C-terminus) (PubMed:26527658). Interacts with ARC5/DRP5B (PubMed:32005784). Plastid equatorial positioning in a discontinuous ring mediated by CDP1 (PubMed:16998069, PubMed:19453460). Colocalizes with ARC5/DRP5B at the chloroplast division site (PubMed:32005784). Expressed in young developing leaves, root tips, shoot apices, and flower buds (sepals, petals, stamens, and pistils), but not in developed tissues. Induced by gibberellic acid (GA). Reduced number of constricted and large chloroplasts due to a blocked plastid division (PubMed:16998069, PubMed:32005784). Accumulation of ARC5/DRP5B in the plastid outer envelope membranes (OEMs) at the midplastid constriction site in the cytoplasm (PubMed:32005784). Truncated N-terminus.