Sub-cellular proteomics has proven to be a powerful approach to link the information contained in sequenced genomes from eukaryotic cells to the functional knowledge provided by studies of cell compartments. Chloroplasts are plant-specific organelles and are the site of photosynthesis and also of many other essential metabolic pathways, like syntheses of amino acids, vitamins, and pigments. They contain several sub-organellar compartments: the envelope (the two-membrane system surrounding the organelle), the stroma (the internal soluble phase), and the thylakoid membranes (the internal membrane system). There is a link between these compartments and the functions of their constitutive proteins. One way to bring into view the sub-proteomes of the chloroplast is to develop proteomic analyses based (1) on the use of highly purified sub-fractions of the chloroplast and (2) on mass spectrometry (MS)-based analyses for protein identification. To illustrate such strategies, this chapter describes the methods for purification of chloroplasts from Arabidopsis leaves and for the specific recovery of highly pure sub-organellar fractions of envelope, stroma, and thylakoids. Subsequently, methods are described to analyze by MS the proteins recovered from these fractions.
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http://dx.doi.org/10.1007/978-1-59745-028-7_2 | DOI Listing |
Bio Protoc
October 2024
UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge, UK.
Protein misfolding fuels multiple neurodegenerative diseases, but existing techniques lack the resolution to pinpoint the location and physical properties of aggregates within living cells. Our protocol describes high-resolution confocal and fluorescent lifetime microscopy (Fast 3D FLIM) of an aggregation probing system. This system involves a metastable HaloTag protein (HT-aggr) labeled with P1 solvatochromic fluorophore, which can be targeted to subcellular compartments.
View Article and Find Full Text PDFUnlabelled: Chloroplasts are organelles composed of sub-organellar compartments-stroma, thylakoids, and starch granules-and are surrounded by outer and inner envelope membranes (OEM and IEM, respectively). The chloroplast OEM and IEM play key roles not only as a barrier separating the chloroplast components from the cytosol but also in the interchange of numerous metabolites and proteins between the chloroplast interior and the cytosol. Fluorescent protein markers for the chloroplast OEM have been widely used to visualize the outermost border of chloroplasts.
View Article and Find Full Text PDFMethods Mol Biol
June 2022
Center for Genetic Medicine Research, Children's National Hospital, Washington, DC, USA.
Enzyme clustering is a phenomenon that involves partitioning of proteins that function together in a common subcellular or sub-organellar compartment. Traditional genetic, biochemical, and biophysical approaches for studying protein-protein interactions in complexes with defined stoichiometry yield inconclusive results when applied to clustered proteins. This chapter describes a combination of approaches to study clustered proteins including co-immunoprecipitation, biochemical co-localization in purified mitochondria, and super resolution imaging of endogenous proteins in situ.
View Article and Find Full Text PDFFront Physiol
January 2022
State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China.
In higher plants, chloroplasts are essential semi-autonomous organelles with complex compartments. As part of these sub-organellar compartments, the sheet-like thylakoid membranes contain abundant light-absorbing chlorophylls bound to the light-harvesting proteins and to some of the reaction center proteins. About half of the thylakoid membrane proteins are encoded by nuclear genes and synthesized in the cytosol as precursors before being imported into the chloroplast.
View Article and Find Full Text PDFRSC Chem Biol
June 2020
Swiss Federal Institute of Technology Lausanne (EPFL), Institute of Chemical Sciences and Engineering 1015 Lausanne Switzerland
Transient associations between numerous organelles-, the endoplasmic reticulum and the mitochondria-forge highly-coordinated, particular environments essential for cross-compartment information flow. Our perspective summarizes chemical-biology tools that have enabled identifying proteins present within these itinerant communities against the bulk proteome, even when a particular protein's presence is fleeting/substoichiometric. However, proteins resident at these ephemeral junctions also experience transitory changes to their interactomes, small-molecule signalomes, and, importantly, functions.
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