Policing Tic 'n' Toc, the doorway to chloroplasts.
The organization of eukaryotic cells into different membrane-enclosed compartments requires an ordered and regulated system for targeting and translocating proteins synthesized in the cytosol across organellar membranes. Protein translocation through integral membrane proteinaceous complexes shares common principles in different organelles, whereas molecular mechanisms and energy requirements are diverse. Translocation into mitochondria and plastids requires most proteins to cross two membranes, and translocation must be regulated to accommodate environmental or metabolic changes. In the last decade, the first ideas were formulated about the regulation of protein translocation into chloroplasts, thereby laying the foundation for this field. Here, we describe recent models for the regulation of translocation by precursor protein phosphorylation, receptor dimerization, redox sensing and calcium signaling. We suggest how these mechanisms might fit within the regulatory framework for the entry of proteins into chloroplasts.
Oreb
Mislav
M
LMU München, Cluster of Excellence CIPS, Department of Biology I, Menziger Str. 67, 80638 München, Germany.
Tews
Ivo
I
Schleiff
Enrico
E
D002462:Cell Membrane / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D018532:Pisum sativum / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D021381:Protein Transport
D008565:Membrane Proteins; D010940:Plant Proteins; D011498:Protein Precursors; C112475:Toc34 protein, plant; D020558:GTP Phosphohydrolases