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Phosphorylation of a proline-directed kinase motif is responsible for structural changes in myogenin
N Hashimoto1, M Ogashiwa, E Okumura
1Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
Abstract:
Myogenin, a member of the MyoD family which governs skeletal muscle differentiation, was identified as a pair of phosphorylated bands on SDS-PAGE during myogenesis. The slow migrating form was found to be hyperphosphorylated myogenin. In vitro phosphorylation by CDC2 kinase caused a prominent reduction in electrophoretic mobility of myogenin. Furthermore, we demonstrated that phosphorylation of the serine residue at position 43 contributes to the modification of myogenin in vivo and in vitro resulting in the reduction in electrophoretic mobility. We propose here that a CDC2-like proline-directed kinase regulates myogenin activity through its phosphorylation.
Insights
Myogenin phosphorylation by CDC2-like kinases regulates skeletal muscle differentiation. This modification, particularly at serine 43, alters myogenin
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Myogenin is a key transcription factor governing skeletal muscle differentiation.
- The MyoD family, including myogenin, plays a crucial role in muscle development.
- Post-translational modifications like phosphorylation can regulate protein function.
Purpose of the Study:
- To investigate the phosphorylation status of myogenin during myogenesis.
- To identify the kinase responsible for myogenin phosphorylation.
- To determine the functional consequences of myogenin phosphorylation.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze protein phosphorylation.
- In vitro kinase assays using CDC2 kinase.
- Site-directed mutagenesis to identify phosphorylation sites.
Main Results:
- Myogenin was identified as a pair of phosphorylated bands on SDS-PAGE during myogenesis.
- A slower migrating band represented hyperphosphorylated myogenin.
- In vitro phosphorylation by CDC2 kinase reduced myogenin's electrophoretic mobility.
- Phosphorylation of serine 43 was identified as a key modification affecting myogenin mobility in vivo and in vitro.
Conclusions:
- A CDC2-like proline-directed kinase regulates myogenin activity.
- Phosphorylation, particularly at serine 43, is a critical mechanism for modulating myogenin function during skeletal muscle differentiation.