• Register
X
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

X

Leaving Community

Are you sure you want to leave this community? Leaving the community will revoke any permissions you have been granted in this community.

No
Yes

The RING finger protein Siah-1 regulates the level of the transcriptional coactivator OBF-1.

The transcriptional coactivator OBF-1, which interacts with Oct-1 and Oct-2 and the octamer site DNA, has been shown to be critical for development of a normal immune response and the formation of germinal centers in secondary lymphoid organs. Here we have identified the RING finger protein Siah-1 as a protein interacting specifically with OBF-1. This interaction is mediated by the C-terminal part of Siah-1 and by residues in the N-terminus of OBF-1, partly distinct from the residues required for formation of a complex with the Oct POU domains and the DNA. Interaction between Siah-1 and OBF-1 leads to downregulation of OBF-1 protein level but not mRNA, and to a corresponding reduction in octamer site-dependent transcription activation. Inhibition of the ubiquitin-proteasome pathway in B cells leads to elevated levels of OBF-1 protein. Furthermore, in immunized mice, OBF-1 protein amounts are dramatically increased in primary activated B cells, without concomitant increase in OBF-1 mRNA. These data suggest that Siah-1 is part of a novel regulatory loop controlling the level of OBF-1 protein in B cells.

Pubmed ID: 11483517

Authors

  • Tiedt R
  • Bartholdy BA
  • Matthias G
  • Newell JW
  • Matthias P

Journal

The EMBO journal

Publication Data

August 1, 2001

Associated Grants

None

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • B-Lymphocytes
  • Binding Sites
  • Boronic Acids
  • Cell Line
  • Cell Line, Transformed
  • Cysteine Endopeptidases
  • Cysteine Proteinase Inhibitors
  • Down-Regulation
  • Humans
  • Mice
  • Molecular Sequence Data
  • Multienzyme Complexes
  • Nuclear Proteins
  • Proteasome Endopeptidase Complex
  • RNA Processing, Post-Transcriptional
  • Trans-Activators
  • Transcriptional Activation
  • Ubiquitin-Protein Ligases
  • Ubiquitins
  • Up-Regulation
  • Zinc Fingers