Fig. 9. A possible working model for AtMinD1-mediated chloroplast division site placement in chloroplasts. (A) In WT AtMinD1 displays functional dimerization and binds to a putative MinC-like protein (?) followed by appropriate polar localization. This ensures correct division machinery placement resulting in a single central constriction site. (B) In AtMinD1(A296G) overexpressing plants, the mutated protein is unable to form dimers but can `activate' a putative MinC-like protein (?) resulting in FtsZ polymerization inhibition and division arrest. (C) In arc11 chloroplasts AtMinD1(A296G) does not dimerize but binds a putative MinC-like protein (?) and due to its mislocalization inappropriate division machinery placement takes place, resulting in multiple constriction site formation.