PTM identification and quantification

Generally, post translational modifications (PTMs) of proteins play an important role in signal transduction pathways, cell death and proliferation (eg phosphorylation), in protein degradation (eg ubiquitination), as well as in intra- and extracellular localisation of proteins (eg glycosylation).

We have successfully established a workflow to analyse and quantify glycosylated proteins on the surface of cells, based on the chemical modification of specific sugar residues and subsequent enrichment of the corresponding glycoproteins. The adjacent label-free LC-MS/MS identification and quantification allows for the determination of cell surfaceome alterations in response to specific stimuli.

Furthermore, we are currently working on a protocol to specifically enrich and analyse phosphorylated peptides in a complex biological sample, in order to identify alterations in phosphorylation dependent signal transduction pathways comparing treated to untreated cellular conditions.