1 research outputs found
Measurement of <i>In Vivo</i> Protein Binding Affinities in a Signaling Network with Mass Spectrometry
Protein interaction networks play
a key role in signal processing.
Despite the progress in identifying the interactions, the quantification
of their strengths lags behind. Here we present an approach to quantify
the <i>in vivo</i> binding of proteins to their binding
partners in signaling-transcriptional networks, by the pairwise genetic
isolation of each interaction and by varying the concentration of
the interacting components over time. The absolute quantification
of the protein concentrations was performed with targeted mass spectrometry.
The strengths of the interactions, as defined by the apparent dissociation
constants, ranged from subnanomolar to micromolar values in the yeast
galactose signaling network. The weak homodimerization of the Gal4
activator amplifies the signal elicited by glucose. Furthermore, combining
the binding constants in a feedback loop correctly predicted cellular
memory, a characteristic network behavior. Thus, this genetic-proteomic
binding assay can be used to faithfully quantify how strongly proteins
interact with proteins, DNA and metabolites