Most proteins required for chloroplast function are encoded in the nuclear genome and have to be translocated into the organelle upon synthesis on cytosolic ribosomes. The translocation is facilitated by a proteinaceous machinery located in the outer and inner chloroplast membrane, the Toc and Tic complexes (translocon at the outer/inner chloroplast membrane). In the past years, many components of these complexes -including receptors, channels and regulatory proteins - have been isolated and characterized biochemically. Recently, the functional analysis of these proteins was complemented by characterization of corresponding loss of function mutants in Arabidopsis thaliana as a model system. Here, we will discuss these in vivo data and the results of expression profiling in the context of current biochemical models.
Keywords: Protein import, Toc components, Tic components, knock out analysis, Arabidopsis thaliana
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