PROSITE documentation PDOC52003
OCA domain profile


The 23 amino acid OCA domain, which binds to class II POU domain-containing transcription factors (TFs) and a DNA octamer motif in a bivalent manner, are found in the POU2AF family of coactivators [1,2]:

  • Vertebrate POU2AF1 (OBF-1, Bob1, OCA-B), a B-cell specific coactivator of class II POU TFs POU2F1 (Oct-1) and POU2F2 (Oct-2).
  • Vertebrate POU2AF2 (C11orf53, OCA-T1), a tuft cell specific coactivator of class II POU TF POU2F3 (Oct-11).
  • Vertebrate POU2AF3 (COLCA2, OCA-T2), a tuft cell specific coactivator of class II POU TF POU2F3 (Oct-11).

An OCA domain is also found in another family of cofactors, the nuclear factor (NF)-kappaB inhibitor zeta (IkappaBzeta) proteins, NF-kappaB regulators which function not only as repressors but also as activators of a selective subset of NF-kappaB target genes [3].

The OCA domain is made of a N-terminal extended polypeptide strand and a C-terminal two-turn α helix (see <PDB:1CQT>) [1].

The profile we developed covers the entire OCA domain.

Last update:

July 2022 / First entry.


Technical section

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

OCA, PS52003; OCA domain profile  (MATRIX)


1AuthorsChasman D. Cepek K. Sharp P.A. Pabo C.O.
TitleCrystal structure of an OCA-B peptide bound to an Oct-1 POU domain/octamer DNA complex: specific recognition of a protein-DNA interface.
SourceGenes. Dev. 13:2650-2657(1999).
PubMed ID10541551

2AuthorsWu X.S. He X.-Y. Ipsaro J.J. Huang Y.-H. Preall J.B. Ng D. Shue Y.T. Sage J. Egeblad M. Joshua-Tor L. Vakoc C.R.
TitleOCA-T1 and OCA-T2 are coactivators of POU2F3 in the tuft cell lineage.
SourceNature 607:169-175(2022).
PubMed ID35576971

3AuthorsMueller A. Hennig A. Lorscheid S. Grondona P. Schulze-Osthoff K. Hailfinger S. Kramer D.
TitleIkappaBzeta is a key transcriptional regulator of IL-36-driven psoriasis-related gene expression in keratinocytes.
SourceProc. Natl. Acad. Sci. U. S. A. 115:10088-10093(2018).
PubMed ID30224457

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