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Identification of Nore1 as a potential Ras effector
1The Diabetes Unit and Medical Services and the Department of Medicine, Harvard Medical School, Massachusetts General Hospital East, Charlestown, Massachusetts 02129, USA.
Abstract:
The small GTP-binding protein Ras is pivotal in transmitting growth and differentiation signals downstream of cell surface receptors. Many observations have indicated that Ras transmits signals from cell surface receptors into multiple pathways via direct interaction with different effectors in mammalian cells. We have identified a novel potential Ras effector or target named Nore1. Nore1 has no significant sequence similarity to known mammalian proteins and lacks an identifiable catalytic domain, but contains sequence motifs that predict DAG_PE binding and SH3 domain binding. We show that Nore1 directly interacts with Ras in vitro in a GTP-dependent manner, and the interaction requires an intact Ras effector domain. Nore1 becomes associated with Ras in situ following activation of epidermal growth factor receptor in COS-7 and in KB cells.
Insights
Researchers discovered Nore1, a novel protein that interacts with the Ras GTP-binding protein. This interaction is crucial for transmitting growth and differentiation signals from cell surface receptors in mammalian cells.
Area of Science:
- Cellular signaling
- Molecular biology
- Protein-protein interactions
Background:
- Ras GTP-binding protein is central to signal transduction pathways.
- Ras mediates signals from cell surface receptors to intracellular pathways via effectors.
Purpose of the Study:
- Identify novel Ras effectors or targets.
- Characterize the interaction between Ras and the newly identified protein, Nore1.
Main Methods:
- In vitro binding assays to test Ras-Nore1 interaction.
- In situ association studies in mammalian cells (COS-7, KB) following receptor activation.
Main Results:
- Identified Nore1, a novel protein with no sequence similarity to known proteins and lacking a catalytic domain.
- Demonstrated direct, GTP-dependent interaction between Nore1 and Ras in vitro.
- Showed Nore1 associates with Ras in cells upon epidermal growth factor receptor activation.
Conclusions:
- Nore1 is a novel Ras effector or target.
- Nore1's interaction with Ras is dependent on Ras's effector domain and GTP-binding state.
- Nore1 is involved in Ras-mediated signaling downstream of growth factor receptors.