Molecular chaperone that hydrolyzes ATP and is associated with the chloroplast protein import apparatus. May function as the motor for chloroplast protein translocation, as translocation requires ATP hydrolysis in the stroma. May interact with a ClpP-like protease involved in degradation of denatured proteins in the chloroplast. Involved in the regulation of chlorophyll b biosynthesis through the destabilization of chlorophyllide a oxygenase (CAO) protein in response to the accumulation of chlorophyll b. Involved in leaf iron homeostasis. Homodimer (PubMed:14593120). May form hexamer and interact with Clp core (PubMed:14593120). Interacts (via N-terminus) with CLPS1 (PubMed:23898032). Interacts with CLPF (PubMed:26419670). The membrane association is important for the in vivo functions. Highly expressed in rosette leaves. Expressed in roots, stems and inflorescences (PubMed:11982939, PubMed:15659100, PubMed:20382967). Expressed in photosynthetic green tissues with high levels in young, developing leaf tissues (PubMed:23898032). By cold and salt stresses. Not induced by heat stress. The Clp repeat (R) domain is important for membrane association and is essential for the in vivo functions, but not for the ATPase activity. Small plants with chlorotic leaves, aberrant chloroplast biogenesis and inefficient chloroplast import of both photosynthetic and non-photosynthetic preproteins (PubMed:15516497, PubMed:15563614, Ref.11, PubMed:15659100, PubMed:17376159, PubMed:17291312, PubMed:20382967). Clpc1 and clpc2 double mutants are embryo lethal when homozygous (PubMed:17376159). Belongs to the ClpA/ClpB family. ClpC subfamily.