DYNAMICS OF HETEROCHROMATIN PROTEINS MEASURED BY FLUORESCENCE CORRELATION SPECTROSCOPY IN LIVING CELLS
Schmiedeberg L., Weißhart K. and Hemmerich P.
Institute for Molecular Biotechnology, Jena, Germany Heterochromatin is a major compartment of the mammalian cell nucleus that represents densely packed and transcriptionally inactive DNA. Heterochromatin protein 1 (HP1) is involved in packaging and maintaining the heterochromatin structure. HP1 proteins belong to the class of non-histone proteins, that bind to modified residues of histones as predicted by the histone code hypothesis. The methylation of lysine 9 of histone H3 is prerequisite for binding of HP1 and maintainance of the repressive state of heterochromatin. In order to investigate the binding properties and the dynamic behaviour of HP1 proteins in living cells, we created HEp-2 cell lines stably expressing GFP-HP1 fusion proteins and determined their dynamic behaviour by Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Correlation Spectroscopy (FCS). Results will be presented which compare the two technologies.
