Mass spectrometry approaches for the redox characterization of protein cysteine residues the case of the transcription factor Pax-8.

Regulation of protein structure and function by redox reactions has emerged as an exciting area of research study. The transduction of a redox signal into a biological response can be mediated in several ways, but a principal mechanism involves the modification of protein cysteine (Cys) residues. Several transcription factors, such as NF-kappaB, Egr-1, AP-1, and Pax, are regulated through redox-based mechanisms. Thus, redox regulation represents a key issue in specifically controlling gene expression. This study describes the combined use of MS procedures and protein-functional assays to investigate the redox state of a protein-regulating gene expression in thyroid, namely Pax-8, a member of the Pax family of transcription factors. Molecular characterization of the modified cysteine residues after various oxidative insults provided information on the mechanisms controlling protein-functional properties.