Calredoxin represents a novel type of calcium-dependent sensor-responder connected to redox regulation in the chloroplast.

Calcium (Ca(2+)) and redox signalling play important roles in acclimation processes from archaea to eukaryotic organisms. Herein we characterized a unique protein from Chlamydomonas reinhardtii that has the competence to integrate Ca(2+)- and redox-related signalling. This protein, designated as calredoxin (CRX), combines four Ca(2+)-binding EF-hands and a thioredoxin (TRX) domain.

A protocol for the identification of protein-protein interactions based on 15N metabolic labeling, immunoprecipitation, quantitative mass spectrometry and affinity modulation.

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in current research and a plethora of methods for their investigation is available. Protein-protein interactions often are highly dynamic and may depend on subcellular localization, post-translational modifications and the local protein environment.

Evidence for a role of VIPP1 in the structural organization of the photosynthetic apparatus in Chlamydomonas.

The vesicle-inducing protein in plastids (VIPP1) was suggested to play a role in thylakoid membrane formation via membrane vesicles. As this functional assignment is under debate, we investigated the function of VIPP1 in Chlamydomonas reinhardtii. Using immunofluorescence, we localized VIPP1 to distinct spots within the chloroplast.

New insights into the roles of molecular chaperones in Chlamydomonas and Volvox.

The unicellular green alga Chlamydomonas reinhardtii has been used as a model organism for many decades, mainly to study photosynthesis and flagella/cilia. Only recently, Chlamydomonas has received much attention because of its ability to produce hydrogen and nonpolar lipids that have promise as biofuels. The best-studied multicellular cousin of Chlamydomonas reinhardtii is Volvox carteri, whose life cycle comprises events that have clear parallels in higher plants and/or animals, making it an excellent system in which to study fundamental developmental processes.

Application of quantitative immunoprecipitation combined with knockdown and cross-linking to Chlamydomonas reveals the presence of vesicle-inducing protein in plastids 1 in a common complex with chloroplast HSP90C.

Knowledge of the interaction partners of a protein of interest may provide important information on its function. Common to currently available tools for the identification of protein-protein interactions, however, is their high rates of false positives. Only recently an assay was reported that allowed for the unequivocal identification of protein-protein interactions in mammalian cells in a single experiment.