About gamma H2AX
Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. Two molecules of each of the four core histones (H2A, H2B, H3, and H4) form an octamer, around which approximately 146 bp of DNA is wrapped in repeating units, called nucleosomes. The linker histone, H1, interacts with linker DNA between nucleosomes and functions in the compaction of chromatin into higher order structures. This gene encodes a replication-independent histone that is a member of the histone H2A family, and generates two transcripts through the use of the conserved stem-loop termination motif, and the polyA addition motif. [provided by RefSeq, Oct 2015]

About Janelia Fluor 646
Janelia Fluor® 646 was developed at the Janelia Campus of the Howard Hughes Medical Institute but is commercialized by other vendors. The Janelia Fluor®s family is unique in that the fluorophores are cell-permeable and are available in photoactivatable forms. These fluorophores were developed for super-resolution microscopy (STED, PALM and STORM) and live-cell microscopy in the HaloTag and SNAP-tag versions. Janelia Fluor® 646 has an excitation peak at 646 nm and an emission peak at 664 nm.