Protein Domain : SAP domain IPR003034

Type	Domain
Description	The SAP motif is a 35-residue motif, which has been named after SAF-A/B, Acinus and PIAS, three proteins known to contain it. The SAP motif is found ina variety of nuclear proteins involved in transcription, DNA repair, RNA processing or apoptotic chromatin degradation. As the sap motif of SAF-A hasbeen shown to be essential for specific DNA binding activity, it has been proposed that it could be a DNA-binding motif [].A multiple alignment of the SAP motif reveals a bipartite distribution of strongly conserved hydrophobic, polar and bulky amino acids separated by aregion that contains a glycine. Secondary structure predictions suggest that the SAP motif could form two alpha helices separated by a turn [].Some proteins known to contain a SAP motif are listed below:Vertebrate scaffold attachment factors A and B (SAF-A/B). These two proteins are heterogeneous nuclear ribonucleoproteins (hnRNPs) that bind toAT-rich chromosomal region. It has been proposed that they couple RNA metabolism to nuclear organisation [, ]. The SAF-A protein is cleaved bycaspase-3 during apoptosis [ ].Mammalian Acinus, a protein which induces apoptotic chromatin condensation after cleavage by caspase-3 []. Acinus also contains a RNA-recognitionmotif. Eukaryotic proteins of the PIAS (protein inhibitor of activated STAT) family. These proteins interact with phosphorylated STAT dimers and inhibitSTAT mediated gene activation. Deletion of the first 50 amino acid residues containing the SAP domain allows the interaction of PIAS1 with STAT1monomer [ ].Plant poly(ADP-ribose) polymerase (PARP). PARP is a nuclear protein that catalyzes the poly(ADP-ribosyl)ation of proteins. It is involved inresponses to mild and severe oxidative stresses, by mediating DNA repair and programmed cell death processes, respectively []. PARP is tightlybound to chromatin or nuclear matrix. Arabidopsis thaliana Arp, an apurinic endonuclease-redox protein.Yeast THO1 protein. It could be involved in the regulation of transcriptional elongation by RNA polymerase II [].Animal Ku70. Together with Ku86, it forms a DNA ends binding complex that is involved in repairing DNA double-strand breaks.Yeast RAD18, a protein involved in DNA repair.Neurospora crassa UVS-2, the homologue of RAD18.
Short Name	SAP_dom