Analysis of Phosphorylation-dependent Protein Interactions of Adhesion and Degranulation Promoting Adaptor Protein (ADAP) Reveals Novel Interaction Partners Required for Chemokine-directed T cell Migration.

Stimulation of T cells leads to distinct changes of their adhesive and migratory properties. Signal propagation from activated receptors to integrins depends on scaffolding proteins such as the adhesion and degranulation promoting adaptor protein (ADAP)(1). Here we have comprehensively investigated the phosphotyrosine interactome of ADAP in T cells and define known and novel interaction partners of functional relevance.

Chemoselective bioconjugation of triazole phosphonites in aqueous media.

Readily accessible and versatile phosphonite building blocks with improved stability against hydrolysis were used for the efficient metal-free functionalization of peptides and proteins in aqueous buffers at low micromolar concentrations. The application of this protocol to the immobilization of a Rasa1-SH2 domain revealed high binding affinity to the human T-cell protein ADAP and supports the applicability of triazole phosphonites for protein modifications without harming their function.

Completion of proteomic data sets by Kd measurement using cell-free synthesis of site-specifically labeled proteins.

The characterization of phosphotyrosine mediated protein-protein interactions is vital for the interpretation of downstream pathways of transmembrane signaling processes. Currently however, there is a gap between the initial identification and characterization of cellular binding events by proteomic methods and the in vitro generation of quantitative binding information in the form of equilibrium rate constants (Kd values). In this work we present a systematic, accelerated and simplified approach to fill this gap: using cell-free protein synthesis with site-specific labeling for pull-down and microscale thermophoresis (MST) we were able to validate interactions and to establish a binding hierarchy based on Kd values as a completion of existing proteomic data sets.

Staudinger-phosphonite reactions for the chemoselective transformation of azido-containing peptides and proteins.

Site-specific functionalization of proteins by bioorthogonal modification offers a convenient pathway to create, modify, and study biologically active biopolymers. In this paper the Staudinger reaction of aryl-phosphonites for the chemoselective functionalization of azido-peptides and proteins was probed. Different water-soluble phosphonites with oligoethylene substituents were synthesized and reacted with unprotected azido-containing peptides in aqueous systems at room temperature in high conversions.

Site-specific modification of proteins by the staudinger-phosphite reaction.

Chemoselective reactions are important tools for the modification of peptides and proteins. Thereby the modification is desired to be site specific and bioorthogonal. Here we describe the site-specific modification of azido-proteins via a Staudinger-type phosphite ligation.

Site-specific functionalisation of proteins by a Staudinger-type reaction using unsymmetrical phosphites.

Unsymmetrical phosphites react efficiently in a Staudinger reaction with p-azido-phenylalanine, which can be applied for the biotinylation of proteins, thereby expanding the scope of the chemoselective Staudinger-phosphite reaction of aryl azides with symmetrical phosphites to the corresponding phosphoramidates.