Involved in plastid protein homeostasis. Component of the chloroplastic Clp protease core complex which consist of at least 16 proteins: CLPP4 (3 copies), CLPP5 (3 copies), CLPR4 (2 copies), ClpP1 (1 copy), CLPP6 (1 copy), CLPR2 (1 copy), CLPT1 (1 copy), CLPT2 (1 copy) and 3 copies of CLPP3 and/or CLPR1 and/or CLPR3 (PubMed:14593120, PubMed:16766689, PubMed:16980539). The core complex is organized in two heptameric rings, one containing CLPP3,4,5,6 in a 1:2:3:1 ratio and the other CLPP1 and CLPR1,2,3,4 in a 3:1:1:1:1 ratio (PubMed:21712416). Embryo lethal (Ref.9). Delayed embryogenesis and albino embryos, with seedling development blocked in the cotyledon stage (PubMed:19525416). Under heterotrophic growth conditions, seedlings develop into small albino to virescent seedlings (PubMed:19525416). Belongs to the peptidase S14 family.