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Selective control of basolateral membrane protein polarity by cdc42
D Cohen1, A Müsch, E Rodriguez-Boulan
1Dyson Institute of Vision Research, Department of Biochemistry, Joan and Sanford Weill Medical College of Cornell University, New York, New York, 10021, USA.
Traffic (Copenhagen, Denmark)
|August 8, 2001
Summary
The rho GTPase cdc42 selectively regulates protein polarity in cells. It affects basolateral proteins but not apical proteins or soluble protein secretion, fine-tuning membrane composition.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cell polarity is crucial for tissue function.
- The rho GTPase cdc42 is known to play a role in cell polarity.
- Previous studies suggested cdc42 affects basolateral protein polarity.
Purpose of the Study:
- To determine if cdc42's effect on protein polarity is selective.
- To investigate cdc42's role in targeting both membrane and soluble proteins.
- To analyze the impact of dominant-negative and GTPase-deficient cdc42 mutants.
Main Methods:
- Utilized Madin-Darby canine kidney (MDCK) cell lines.
- Overexpressed mutant forms of cdc42 (GTPase-deficient and dominant-negative).
- Analyzed the polarity of newly synthesized apical and basolateral membrane proteins and endogenous soluble proteins.
Main Results:
- Mutant cdc42 did not alter apical membrane protein targeting.
- Mutant cdc42 reversed the apical distribution of exogenous basolateral membrane proteins.
- GTPase-deficient cdc42 did not affect the polarized exocytosis of endogenous soluble proteins.
Conclusions:
- Cdc42 exhibits exquisite selectivity in regulating polarized protein targeting.
- This selective regulation allows cells to fine-tune membrane composition.
- This mechanism is important during development, migration, and in response to injury.