Mapping and identification of interferon gamma-regulated HeLa cell proteins separated by immobilized pH gradient two-dimensional gel electrophoresis.

Interferon gamma (IFN-gamma) is a potent immunomodulatory lymphokine, secreted by activated T-lymphocytes and NK-cells during the cellular immune response. Actions of IFN-gamma are mediated through binding to the IFN-gamma-receptor, present on most cells, and the subsequent activation of a great magnitude of IFN-gamma responsive genes has been reported previously. Our goal is to identify and map IFN-gamma-regulated HeLa cell proteins to the two-dimensional polyacrylamide gel electrophoresis with the immobilized pH gradient (IPG) two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) system. A semiconfluent layer of HeLa cells was grown on tissue culture plates, and changes in protein expression due to 100 U/mL IFN-gamma were investigated at different periods after treatment, using pulse labeling with [35S]methionine/cysteine in combination with 2-D PAGE (IPG). The identity of eight protein spots was elucidated by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), and several variants of the IFN-gamma-inducible tryptophanyl-tRNA synthetase (hWRS) were detected by immunoblotting.