Related Experiment Video

Updated: Nov 19, 2025

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
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Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

Published on: June 15, 2017

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Structure and noncanonical Cdk8 activation mechanism within an Argonaute-containing Mediator kinase module

Yi-Chuan Li1, Ti-Chun Chao1, Hee Jong Kim2

  • 1Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA.

Science Advances
|February 1, 2021
PubMed

Insights

Researchers reveal the structure of the Cdk8 kinase module (CKM), explaining how Med12 activates Cdk8 and uncovering Med13's Argonaute-like structure. This provides insights into CKM function and dysfunction in diseases like cancer.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • The Cdk8 kinase module (CKM) is crucial for regulating RNA polymerase II transcription.
  • Pathogenic mutations in CKM subunits are linked to neurodevelopmental disorders and cancer.
  • The intact CKM structure and Cdk8 activation mechanisms remain poorly understood.

Purpose of the Study:

  • To determine the cryo-electron microscopy structure of the Saccharomyces cerevisiae CKM.
  • To elucidate the mechanism of Med12-dependent Cdk8 activation.
  • To characterize the structural features of Med13 within the CKM.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) of Saccharomyces cerevisiae CKM.
  • Structural analysis and molecular modeling.
  • Biochemical assays to study protein interactions and activation.

Main Results:

  • A high-resolution cryo-EM structure of the CKM was obtained, refining existing models.
  • Med12 stabilizes the Cdk8 activation loop, explaining Med12-dependent Cdk8 activation.
  • Conserved Med12 residues crucial for Cdk8 activation are frequently mutated in human tumors.
  • Med13 exhibits an unexpected Argonaute-like bi-lobal architecture.

Conclusions:

  • The study provides a structural basis for understanding CKM function and its role in disease.
  • Med12-dependent Cdk8 activation is mediated by stabilizing the T-loop via specific residues.
  • Med13's Argonaute-like structure suggests a novel regulatory role in transcriptional modulation.

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