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. The FACT complex is probably also involved in phosphorylation of 'Ser-392' of p53/TP53 via its association with CK2 (casein kinase II). Binds specifically to double-stranded DNA and at low levels to DNA modified by the antitumor agent cisplatin. May potentiate cisplatin-induced cell death by blocking replication and repair of modified DNA. Also acts as a transcriptional coactivator for p63/TP63. Interacts with MYOG (via C-terminal region) (By similarity). Component of the FACT complex, a stable heterodimer of SSRP1 and SUPT16H. Also a component of a CK2-SPT16-SSRP1 complex which forms following UV irradiation, composed of SSRP1, SUPT16H, CSNK2A1, CSNK2A2 and CSNK2B. Binds to histone H3-H4 tetramers, but not to intact nucleosomes. Identified in a centromere complex containing histones H2A, H2B and H4, and at least CENPA, CENPB, CENPC, CENPT, CENPN, HJURP, SUPT16H, SSRP1 and RSF1. Interacts with isoform gamma of TP63. Interacts with FYTTD1/UIF (By similarity). Interacts with SRF (PubMed:10336466). Interacts with NEK9 (By similarity). Colocalizes with RNA polymerase II on chromatin. Recruited to actively transcribed loci. Phosphorylated by CK2 following UV but not gamma irradiation. Phosphorylation inhibits its DNA-binding activity (By similarity). Ubiquitinated. Polyubiquitinated following caspase cleavage resulting in degradation of the N-terminal ubiquitinated part of the cleaved protein (By similarity). Sumoylated. Belongs to the SSRP1 family.