Transcription factor Sp3
Domain
The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors.
Function
Transcriptional factor that can act as an activator or repressor depending on isoform and/or post-translational modifications. Binds to GT and GC boxes promoter elements. Competes with SP1 for the GC-box promoters. Weak activator of transcription but can activate a number of genes involved in different processes such as cell-cycle regulation, hormone-induction and house-keeping.
Post-translational modifications
Not glycosylated.
Acetylated by histone acetyltransferase p300, deacetylated by HDACs. Acetylation/deacetylation states regulate transcriptional activity. Acetylation appears to activate transcription. Alternate sumoylation and acetylation at Lys-551 also control transcriptional activity. Ceramides can also regulate acetylation/deacetylation events through altering the interaction of HDAC with SP3. In vitro, C(18)-ceramides, but not C(16)-ceramides, increase the interaction of HDAC1 with SP3 and enhance the deacetylation of SP3 and the subsequent repression of the TERT promoter.
Sumoylated on all isoforms. Sumoylated on 2 sites in longer isoforms with Lys-551 being the major site. Sumoylation at this site promotes nuclear localization to the nuclear periphery, nuclear dots and PML nuclear bodies. Sumoylation on Lys-551 represses the transactivation activity, except for the largest isoform, L-Sp3, which has little effect on transactivation. Alternate sumoylation and acetylation at Lys-551 also control transcriptional activity.
Sequence Similarities
Belongs to the Sp1 C2H2-type zinc-finger protein family.
Tissue Specificity
Ubiquitously expressed.
Cellular localization
- Nucleus
- Nucleus
- PML body
- Localizes to the nuclear periphery and in nuclear dots when sumoylated. Some localization in PML nuclear bodies.
Alternative names
Transcription factor Sp3, SPR-2, SP3