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Related Concept Videos

The JAK-STAT Signaling Pathway01:20

The JAK-STAT Signaling Pathway

Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as  SH2...
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Tail-anchoring of Proteins in the ER Membrane

Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...
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Energy to Drive Translocation

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Generally, polypeptides are unfolded by two distinct...
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Protein Complex Assembly

Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types.  Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
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Post-translational Translocation of Proteins to the RER01:27

Post-translational Translocation of Proteins to the RER

A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
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Cotranslational Protein Translocation

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Analyzing Protein Dynamics Using Hydrogen Exchange Mass Spectrometry
11:37

Analyzing Protein Dynamics Using Hydrogen Exchange Mass Spectrometry

Published on: November 29, 2013

STAT3 interacts directly with Hsp90.

Earl Prinsloo1, Adam H Kramer, Adrienne L Edkins

  • 1Biomedical Biotechnology Research Unit, Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, South Africa. e.prinsloo@ru.ac.za

IUBMB Life
|January 25, 2012
PubMed
Summary
This summary is machine-generated.

Heat shock protein 90 (Hsp90) directly binds to signal transducer and activator of transcription 3 (STAT3). This interaction requires STAT3's DNA-binding domain, impacting oncogenesis and immune signaling pathways.

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Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • Protein Interactions

Background:

  • Heat shock protein 90 (Hsp90) modulates signal transduction pathways.
  • Signal transducer and activator of transcription 3 (STAT3) is crucial for cytokine signaling and implicated in cancer and immune disorders.
  • Previous studies indicated Hsp90 and STAT3 colocalize and form complexes.

Purpose of the Study:

  • To investigate the direct interaction between Hsp90 and STAT3.
  • To determine the role of STAT3's DNA-binding domain in this interaction.
  • To analyze the impact of STAT3 activation state on Hsp90 binding.

Main Methods:

  • Surface plasmon resonance spectroscopy to assess direct binding affinity.
  • Site-directed mutagenesis of STAT3 (phosphomimetic and DNA-binding domain mutations).
  • Confocal laser scanning microscopy for in vivo colocalization studies in MCF7 cells.

Main Results:

  • A direct, high-affinity interaction between Hsp90β and STAT3β was confirmed, independent of ATP.
  • STAT3's DNA-binding domain (residues 414/417) is essential for high-affinity interaction with Hsp90β.
  • Mutations disrupting the DNA-binding domain reduced Hsp90 binding in vitro and in vivo, despite normal nuclear translocation.

Conclusions:

  • Hsp90 directly binds to STAT3 with high affinity.
  • The DNA-binding domain of STAT3 is critical for its interaction with Hsp90.
  • This interaction may be a target for modulating STAT3-driven oncogenesis and immune responses.