PROSITE documentation PDOC50800
SAP motif profile


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 in a variety of nuclear proteins involved in transcription, DNA repair, RNA processing or apoptotic chromatin degradation. As the sap motif of SAF-A has been shown to be essential for specific DNA binding activity, it has been proposed that it could be a DNA-binding motif [1,2].

A multiple alignment of the SAP motif reveals a bipartite distribution of strongly conserved hydrophobic, polar and bulky amino acids separated by a region that contains a glycine. Secondary structure predictions suggest that the SAP motif could form two α helices separated by a turn [1].

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 to AT-rich chromosomal region. It has been proposed that they couple RNA metabolism to nuclear organization [2,3,4]. The SAF-A protein is cleaved by caspase-3 during apoptosis [2,5].
  • Mammalian Acinus, a protein which induces apoptotic chromatin condensation after cleavage by caspase-3 [6]. Acinus also contains a RNA-recognition motif.
  • Eukaryotic proteins of the PIAS (protein inhibitor of activated STAT) family. These proteins interact with phosphorylated STAT dimers and inhibit STAT mediated gene activation. Deletion of the first 50 amino acid residues containing the SAP domain allows the interaction of PIAS1 with STAT1 monomer [7].
  • Plant poly(ADP-ribose) polymerase (PARP). PARP is a nuclear protein that catalyzes the poly(ADP-ribosyl)ation of proteins. It is involved in responses to mild and severe oxidative stresses, by mediating DNA repair and programmed cell death processes, respectively [8]. PARP is tightly bound 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 [9].
  • 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 homolog of RAD18.

The profile we developed cover the entire SAP motif.

Last update:

February 2003 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

SAP, PS50800; SAP motif profile  (MATRIX)


1AuthorsAravind L. Koonin E.V.
TitleSAP - a putative DNA-binding motif involved in chromosomal organization.
SourceTrends Biochem. Sci. 25:112-114(2000).
PubMed ID10694879

2AuthorsGoehring F. Schwab B.L. Nicotera P. Leist M. Fackelmayer F.O.
SourceEMBO J. 16:7361-7371(1997).

3AuthorsWeighardt F. Cobianchi F. Cartegni L. Chiodi I. Villa A. Riva S. Biamonti G.
TitleA novel hnRNP protein (HAP/SAF-B) enters a subset of hnRNP complexes and relocates in nuclear granules in response to heat shock.
SourceJ. Cell Sci. 112:1465-1476(1999).
PubMed ID10212141

4AuthorsNayler O. Stratling W. Bourquin J.P. Stagljar I. Lindemann L. Jasper H. Hartmann A.M. Fackelmayer F.O. Ullrich A. Stamm S.
TitleSAF-B protein couples transcription and pre-mRNA splicing to SAR/MAR elements.
SourceNucleic Acids Res. 26:3542-3549(1998).
PubMed ID9671816

5AuthorsKipp M. Schwab B.L. Przybylski M. Nicotera P. Fackelmayer F.O.
TitleApoptotic cleavage of scaffold attachment factor A (SAF-A) by caspase-3 occurs at a noncanonical cleavage site.
SourceJ. Biol. Chem. 275:5031-5036(2000).
PubMed ID10671544

6AuthorsSahara S. Aoto M. Eguchi Y. Imamoto N. Yoneda Y. Tsujimoto Y.
TitleAcinus is a caspase-3-activated protein required for apoptotic chromatin condensation.
SourceNature 401:168-173(1999).
PubMed ID10490026

7AuthorsLiao J. Fu Y. Shuai K.
TitleDistinct roles of the NH2- and COOH-terminal domains of the protein inhibitor of activated signal transducer and activator of transcription (STAT) 1 (PIAS1) in cytokine-induced PIAS1-Stat1 interaction.
SourceProc. Natl. Acad. Sci. U.S.A. 97:5267-5272(2000).
PubMed ID10805787

8AuthorsAmor Y. Babiychuk E. Inze D. Levine A.
TitleThe involvement of poly(ADP-ribose) polymerase in the oxidative stress responses in plants.
SourceFEBS Lett. 440:1-7(1998).
PubMed ID9862413

9AuthorsPiruat J.I. Aguilera A.
TitleA novel yeast gene, THO2, is involved in RNA pol II transcription and provides new evidence for transcriptional elongation-associated recombination.
SourceEMBO J. 17:4859-4872(1998).
PubMed ID9707445

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