Decoding Proline-Rich Sequence Recognition By Epitope-Based Proteomics

Multifunctional protein surfaces pose a major challenge for the understanding of an individual protein's contribution to cellular signalling. Deconvolution of network connectivities for individual epitopes by combining site‐specific inhibition with stable isotope labelling of amino acids in cell culture (SILAC)/mass spectrometry provides a powerful tool of investigation and has been applied to signalling adaptors of the proline‐rich sequence (PRS) recognition family. We show that formation of the pre‐spliceosome and of mRNA surveillance complexes depend on PRS recognition and that PRS hubs within these complexes drive the assembly of dynamic initiator complexes (Kofler et al., Mol. Cell. Proteom 8, 2461–2473; Schlundt et al., Mol. Cell. Proteom. 8, 2474–2486 (2009)). Our approach thereby provides complementary information to knock‐down and knock‐out models of protein function and it also reveals the “moonlighting” potential of a given protein surface within the cellular context. This work was supported by grants FG806, SFB740 and SFB765 of the Deutsche Forschungsgemeinschaft.