Abstract
Chloroplasts are metabolically complex organelles that participate in a diverse array of biochemical processes in addition to their well known role in photosynthesis. Consistent with their functional complexity, chloroplasts are structurally complex organelles. They possess three different lipid bilayer membranes enclosing three different aqueous compartments (Figure 1). Each membrane and each aqueous compartment has a unique set of proteins and enzyme activities that reflect their respective functions. Because the plastid genome has a limited coding capacity, most chloroplastic proteins are encoded by nuclear genes and synthesized in the cytoplasm as higher molecular weight precursors (Figure 1). The extra region of peptide is present at the amino terminus of a precursor, and is called a transit peptide because of its importance in directing the precursor into chloroplasts. Understanding how these precursor proteins are targeted from the cytoplasm to their proper location within chloroplasts is a major challenge and recent progress in this effort is briefly reviewed in this paper. This subject has been the topic of several reviews in recent years and readers should consult them for further details (de Boer and Weisbeek, 1991; Cline and Henry, 1996; Fuks and Schnell, 1997; Gray and Row, 1995; Kouranov and Schnell, 1996; Lübeck et al., 1997; Schnell, 1995; Theg and Scott, 1993).
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Keegstra, K., Akita, M., Davila-Aponte, J., Froehlich, J., Nielsen, E., Reumann, S. (1998). Transport of Cytoplasmically Synthesized Proteins into Chloroplasts. In: Lo Schiavo, F., Last, R.L., Morelli, G., Raikhel, N.V. (eds) Cellular Integration of Signalling Pathways in Plant Development. NATO ASI Series, vol 104. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-72117-5_3
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DOI: https://doi.org/10.1007/978-3-642-72117-5_3
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