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Protein-protein interactions. Anders Riis Kristensen. Why study protein-proteins interactions?. G uilt by association Functional characterization of proteins Global phenomenon in the cell Modularity of proteins in protein complexes
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Protein-protein interactions Anders Riis Kristensen
Why study protein-proteins interactions? • Guilt by association • Functional characterization of proteins • Global phenomenon in the cell • Modularity of proteins in protein complexes • Estimated 90 % of proteins serve as components of protein complexes, in most, if not all living organisms • Proteins interaction networks are scale-free • Few proteins many interactions, many proteins few interactions
Protein interactions • Scope of study • Focused studies • FRET • AP-MS • Native mass spectrometry • Global studies • AP-MS • Y2H • SEC-PCP-SILAC
Quantitative AP-MS • To differentiating specific interaction from non specific
AP-MRM Allows for quantitatively studying a number of proteins consistently Nature Biotechnology 29, 653-658 (2011)
Problems with present techniques • Not suitable to study the human interactome • Mass spectrometry based techniques generates many samples (>30.000) • Require often tagging of proteins • Interfere with interacting proteins • Can lead to mis-localisation • Can not easily detect dynamic interactions
Co migration methods J Cell Biol. 1981 Sep;90(3):568-76. Chen V, 2012, in press
Co-migration methods used to study organelles Centrosome proteins Proteasome proteins Foster LJ, Cell, 125, 2006 Jakobsen L, The EMBO Journal, 30, 2011
Workflow for Protein Correlation Profiling-SILAC • PCP-SILAC has traditionally been used to profile organelles using density gradients1-3. “LYS 4” “ARG 6” “LYS 0” “ARG 0” 100K MWCO 100K MWCO SEC SEC 1. Andersen, JS; Nature426, 570–574 (2003) 2. Foster, LJ; Cell125, 187–199 (2006) 3. Jakobsen L ; The EMBO Journal30, 1520–1535 (2011) Mass Spectrometry
Data analysis using clustering Signalosome Prefoldin Proteasome Core Subunit Ratio M/L Proteasome Regulatory Subunit Fractions 0 5
Summary of data analysis 3421 Proteins Identified 8935 Gaussian peaks 7209 Binary Interactions 291 Protein complexes
Workflow for Dynamic PCP- SILAC +EGF “LYS 0” “ARG 0” “LYS 4” “ARG 6” “LYS 8” “ARG 10” 100K MWCO 100K MWCO 100K MWCO SEC SEC Mass spectrometry
Workflow for Dynamic ppSILAC +EGF “LYS 0” “ARG 0” “LYS 4” “ARG 6” “LYS 8” “ARG 10” 100K MWCO 100K MWCO 100K MWCO SEC SEC Mass spectrometry
Identification of dynamic interactions • Identified 351 proteins that changed interaction following 20 min. EGF stimulation. STAM Aranda B; Nuc. Acids Research38 (2001) Olsen JV; Cell127 (2006) Blagoev B; Nat. Biotechnol22 (2004) Argenzio E; Mol. Sys. Biol.7 (2011)
Validation of complexes “LYS 0” “ARG 0” “LYS 4” “ARG 6” “LYS 8” “ARG 10” 100K MWCO 100K MWCO 100K MWCO Add antibody SEC SEC SEC Mass spectrometry