FunctionMultitasking protein, involved in apoptosis, transcription, nucleosome assembly and histone binding. Isoform 2 anti-apoptotic activity is mediated by inhibition of the GZMA-activated DNase, NME1. In the course of cytotoxic T-lymphocyte (CTL)-induced apoptosis, GZMA cleaves SET, disrupting its binding to NME1 and releasing NME1 inhibition. Isoform 1 and isoform 2 are potent inhibitors of protein phosphatase 2A. Isoform 1 and isoform 2 inhibit EP300/CREBBP and PCAF-mediated acetylation of histones (HAT) and nucleosomes, most probably by masking the accessibility of lysines of histones to the acetylases. The predominant target for inhibition is histone H4. HAT inhibition leads to silencing of HAT-dependent transcription and prevents active demethylation of DNA. Both isoforms stimulate DNA replication of the adenovirus genome complexed with viral core proteins; however, isoform 2 specific activity is higher.
Tissue specificityWidely expressed. Low levels in quiescent cells during serum starvation, contact inhibition or differentiation. Highly expressed in Wilms' tumor.
Involvement in diseaseNote=A chromosomal aberration involving SET is found in some cases of acute undifferentiated leukemia (AUL). Translocation t(6;9)(q21;q34.1) with NUP214/CAN.
Sequence similaritiesBelongs to the nucleosome assembly protein (NAP) family.
DomainThe C-terminal acidic domain mediates the inhibition of histone acetyltransferases and is required for the DNA replication stimulatory activity.
Post-translational modificationsIsoform 2 is phosphorylated on Ser-15 and Thr-23. Isoform 2 is acetylated on Lys-11. Some glutamate residues are glycylated by TTLL8. This modification occurs exclusively on glutamate residues and results in a glycine chain on the gamma-carboxyl group. N-terminus of isoform 1 is methylated by METTL11A/NTM1. Mainly trimethylated.
Cellular localizationCytoplasm > cytosol. Endoplasmic reticulum. Nucleus > nucleoplasm. In the cytoplasm, found both in the cytosol and associated with the endoplasmic reticulum. Following CTL attack, moves rapidly to the nucleus, where it is found in the nucleoplasm, avoiding the nucleolus. Similar translocation to the nucleus is also observed for lymphocyte-activated killer cells after the addition of calcium. The SET complex is associated with the endoplasmic reticulum.