• Proteome analysis of distinct developmental stages of human natural killer (NK) cells.

      Scheiter, Maxi; Lau, Ulrike; van Ham, Marco; Bulitta, Björn; Gröbe, Lothar; Garritsen, Henk; Klawonn, Frank; König, Sebastian; Jänsch, Lothar; Research Group Cellular Proteomics, Helmholtz Centre for Infection Research, HZI, Inhoffenstraβe 7, D-38124 Braunschweig, Germany. (2013-05)
      The recent Natural Killer (NK) cell maturation model postulates that CD34(+) hematopoietic stem cells (HSC) first develop into CD56(bright) NK cells, then into CD56(dim)CD57(-) and finally into terminally maturated CD56(dim)CD57(+). The molecular mechanisms of human NK cell differentiation and maturation however are incompletely characterized. Here we present a proteome analysis of distinct developmental stages of human primary NK cells, isolated from healthy human blood donors. Peptide sequencing was used to comparatively analyze CD56(bright) NK cells versus CD56(dim) NK cells and CD56(dim)CD57(-) NK cells versus CD56(dim)CD57(+) NK cells and revealed distinct protein signatures for all of these subsets. Quantitative data for about 3400 proteins were obtained and support the current differentiation model. Furthermore, 11 donor-independently, but developmental stage specifically regulated proteins so far undescribed in NK cells were revealed, which may contribute to NK cell development and may elucidate a molecular source for NK cell effector functions. Among those proteins, S100A4 (Calvasculin) and S100A6 (Calcyclin) were selected to study their dynamic subcellular localization. Upon activation of human primary NK cells, both proteins are recruited into the immune synapse (NKIS), where they colocalize with myosin IIa.
    • Proteomics analysis of protein kinases by target class-selective prefractionation and tandem mass spectrometry.

      Wissing, Josef; Jänsch, Lothar; Nimtz, Manfred; Dieterich, Guido; Hornberger, Renate; Kéri, György; Wehland, Jürgen; Daub, Henrik; Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany. (2007-03)
      Protein kinases constitute a large superfamily of enzymes with key regulatory functions in nearly all signal transmission processes of eukaryotic cells. However, due to their relatively low abundance compared with the vast majority of cellular proteins, currently available proteomics techniques do not permit the comprehensive biochemical characterization of protein kinases. To address these limitations, we have developed a prefractionation strategy that uses a combination of immobilized low molecular weight inhibitors for the selective affinity capture of protein kinases. This approach resulted in the direct purification of cell type-specific sets of expressed protein kinases, and more than 140 different members of this enzyme family could be detected by LC-MS/MS. Furthermore the enrichment technique combined with phosphopeptide fractionation led to the identification of more than 200 different phosphorylation sites on protein kinases, which often remain occluded in global phosphoproteome analysis. As the phosphorylation states of protein kinases can provide a readout for the signaling activities within a cellular system, kinase-selective phosphoproteomics based on the procedures described here has the potential to become an important tool in signal transduction analysis.