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K-ras4B and prenylated proteins lacking "second signals" associate dynamically with cellular membranes
John R Silvius1, Pinkesh Bhagatji, Rania Leventis
1Department of Biochemistry, McGill University, Montréal, Québec H3G 1Y6, Canada. john.r.silvius@mcgill.ca
Molecular Biology of the Cell
|October 21, 2005
Summary
We used rapamycin-induced protein dimerization to study K-ras4B dynamics. K-ras4B rapidly moves between the plasma membrane and mitochondria, revealing its dynamic subcellular localization.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- K-ras4B is a small GTPase critical for cell signaling.
- Its plasma membrane localization is essential for function, but its dynamics are not fully understood.
- Lipid modifications play a key role in directing proteins to cellular membranes.
Purpose of the Study:
- To investigate the dynamic subcellular localization of K-ras4B.
- To understand the reversibility of K-ras4B plasma membrane association.
- To explore how lipid modifications influence protein trafficking.
Main Methods:
- Rapamycin-regulated protein heterodimerization.
- Fluorescence microscopy.
- Analysis of fluorescent protein fusions with K-ras4B and lipid-modified sequences.
Main Results:
- Fluorescent proteins with single lipid modifications rapidly translocated to mitochondria upon rapamycin addition.
- Plasma membrane-anchored constructs showed limited or no mitochondrial transfer.
- K-ras4B and its targeting sequence demonstrated rapid, reversible transfer from the plasma membrane to mitochondria within minutes.
Conclusions:
- K-ras4B exhibits dynamic plasma membrane association.
- This rapid reversibility suggests a mechanism for subcellular redistribution.
- The findings provide insights into K-ras4B function and regulation.