Component of the FACT complex, a general chromatin factor that acts to reorganize nucleosomes. The FACT complex is involved in multiple processes that require DNA as a template such as mRNA elongation, DNA replication and DNA repair. During transcription elongation the FACT complex acts as a histone chaperone that both destabilizes and restores nucleosomal structure. It facilitates the passage of RNA polymerase II and transcription by promoting the dissociation of one histone H2A-H2B dimer from the nucleosome, then subsequently promotes the reestablishment of the nucleosome following the passage of RNA polymerase II. Component of the FACT complex (also called the DUF complex), a stable heterodimer of ssrp1 and supt16h. May also be a component of a ck2-spt16-ssrp1 complex composed of ssrp1, supt16h, csnk2a1, csnk2a2 and csnk2b. The FACT complex may also interact with vcp. The Glu-rich acidic region in C-terminus is essential for FACT activity. Belongs to the peptidase M24 family. SPT16 subfamily. Although related to the peptidase M24 family, this protein lacks conserved active site residues suggesting that it may lack peptidase activity. Contaminating sequence. Potential poly-A sequence.