Related Experiment Videos
Human T-cell mitogen-activated protein kinase kinases are related to yeast signal transduction kinases
R Seger1, D Seger, F J Lozeman
1Department of Pharmacology, University of Washington, Seattle 98195.
Abstract:
Mitogen-activated protein (MAP) kinase kinases, intermediates in a growth factor-stimulated protein kinase cascade, are dual specificity protein kinases that specifically phosphorylate and activate MAP kinases in response to extracellular signals. Here, we report the cloning of two forms of cDNA that encode this protein from human T-cells. MKK1a encodes a protein with predicted molecular size of 43,439 Da. Overexpression of this clone in COS cells led to elevated levels of protein and phorbol ester-stimulated MAP kinase kinase activity, confirming that MKK1a encodes the predicted protein. MKK1b, which appears to be an alternatively spliced form of the MKK1a gene, encodes a protein with predicted molecular size of 40,745 Da. Northern analysis revealed that the MKK1 cDNA hybridizes with a single 2.6-kilobase mRNA species in all human tissues examined. Sequence comparison shows homology to a group of yeast kinases that participate in signal transduction and to subdomain XI of other dual specificity kinase.
Insights
Researchers cloned two forms of Mitogen-activated protein (MAP) kinase kinase (MKK1) from human T-cells. These findings confirm MKK1a
Area of Science:
- Molecular Biology
- Cell Signaling
- Biochemistry
Background:
- Mitogen-activated protein (MAP) kinase kinases (MKKs) are key intermediates in growth factor-stimulated protein kinase cascades.
- They act as dual specificity protein kinases, phosphorylating and activating MAP kinases in response to extracellular signals.
Purpose of the Study:
- To clone and characterize two forms of human MKK1 cDNA from T-cells.
- To confirm the functional activity of the cloned MKK1a protein.
Main Methods:
- Cloning of two cDNA forms (MKK1a and MKK1b) from human T-cells.
- Overexpression of MKK1a in COS cells to assess protein levels and kinase activity.
- Northern blot analysis to examine MKK1 mRNA expression across human tissues.
- Sequence comparison with known kinases.
Main Results:
- MKK1a cDNA encodes a protein of 43,439 Da; MKK1b encodes a protein of 40,745 Da, likely an alternatively spliced form.
- Overexpression of MKK1a increased MKK activity in COS cells.
- MKK1 cDNA hybridized to a single 2.6-kilobase mRNA species in all human tissues.
- Sequence homology was found with yeast kinases involved in signal transduction.
Conclusions:
- The study successfully cloned and characterized two forms of human MKK1.
- MKK1a is functionally active and plays a role in cellular signaling pathways.
- MKK1 is expressed ubiquitously across human tissues, suggesting a fundamental role in cellular processes.