Probably involved in the regulation of the fatty acid metabolic process in chloroplasts, especially chloroplastic galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG). Interacts (via J-like domain) with ARC6 (via J domain). Altered fatty acid profiles with a slight increase of 16:1delta7 and 18:1delta9 leaf monounsaturated fatty acids and subtle decrease of 16:3 and 18:3 polyunsaturated fatty acids, chloroplastic galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) being the main lipid types affected (PubMed:22028775). Abnormally large chloroplasts (PubMed:22028775). The double mutant arc6 cjd1 exhibits both phenotypes of single mutants cjd1 and arc6 including altered fatty acid profiles and heterogeneous chloroplasts sizes and shapes, respectively (PubMed:22028775).