SCAN:PTMomics – a potpourri of experimental approaches

ITQB Scan Seminar

Title: PTMomics – a potpourri of experimental approaches

Speaker: Ana Varela Coelho

From: Head of Mass Spectrometry Laboratory

Abstract:

The modification of proteins post-translationally is of great importance in protein activity and cellular metabolism regulation. The protein amino acids may be modified after translation, altering the proteins and peptides molecular masses, which can complicate the identification of proteins, in particular from organisms that do not have their genomes sequenced.

There are over 400 post-translational modifications of proteins described. The most common and naturally occurring PTMs include phosphorylation, glycosylation, cleavage, formylation, methionine oxidation and ubiquitination. There are multiple experimental approaches that can be used for their detection and for the characterization and quantification of the generated protein isoforms. In order to achieve these aims it is important to individualize the isoforms either at the protein or at the peptide level. In that respect, 2D electrophoresis has been a helpful separation method, which can be coupled with specific stains or antibody interactions for PTM extensive detection and quantification and with mass spectrometry (MS) for isoform characterization and localization of modified amino acid residues.

Depending on the type of PTM under study different MS strategies tend to be selected mainly due to their lability and chemical specificities. Additionally, in some cases it is indispensable to perform previous enrichment protocols. Several case studies involving PTM identifications, characterizations and quantifications will be presented.