Fig. 6.

Summarizing overview of the consequences of reduced accumulation of the ClpPR complex. The nucleus-encoded proteins are imported through the Toc/Tic translocon in the chloroplast envelope followed by removal of the N-terminal chloroplast transit peptide (cTP), folding, and assembly (61, 117). Proteins destined for the thylakoid membrane system, including the thylakoid lumen, are targeted following different pathways and involving different sorting components (118). The chloroplast-encoded proteins are synthesized on 70 S ribosomes either in the chloroplast stroma or at the thylakoid surface (118). Proteins that were significantly up-regulated in clpr2-1 seedlings are: Tic110 (1); PreP1,2 (2); cpHSP70 and CPN60 (3); cpHSP90 (4); ClpB3 (5); EF-BipA, EF-TU, and DEAD box helicase RH3 (6); FIB1a,B (8); GGR (9); HDS (10); THI1 (11); GUN5 and CHLI-1 (12); and water dikinase (WDK)/SEX1 (13). Proteins that were significantly down-regulated in clpr2-1 seedlings are components of PSII, PSI, and ATP synthase (7). Chl, chlorophyll; PPP, triphosphate; GG, geranylgeranyl; GGPP, geranylgeranyl diphosphate; vit, vitamin.