Related Experiment Videos
Aquaporin-0 membrane junctions form upon proteolytic cleavage.
Tamir Gonen1, Yifan Cheng, Joerg Kistler
1Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Journal of Molecular Biology
|September 8, 2004
Summary
Aquaporin-0 (AQP0) functions as a water channel in the lens cortex but transforms into an adhesion molecule in the lens core. This functional shift is due to C-terminal cleavage, enhancing cell adhesion.
Area of Science:
- Biochemistry
- Cell Biology
- Structural Biology
Background:
- Aquaporin-0 (AQP0) is the primary water channel protein in lens fiber cells.
- AQP0 is the most abundant intrinsic membrane protein in the eye lens.
- AQP0 undergoes cleavage from full-length to truncated forms in the lens core.
Purpose of the Study:
- To investigate the structural and functional changes of AQP0 during lens maturation.
- To elucidate the role of AQP0 cleavage in lens fiber cell adhesion.
- To analyze the conformational changes of AQP0 using electron crystallography.
Main Methods:
- Reconstitution of AQP0 from lens cortex (full-length) and core (truncated) fractions.
- Formation and analysis of two-dimensional (2D) crystals of AQP0.
- Electron diffraction and projection mapping of AQP0 crystals.
Main Results:
- Full-length AQP0 formed single-layered 2D crystals.
- Truncated AQP0 from the lens core formed double-layered 2D crystals.
- Cleavage of AQP0's C-terminus enhanced extracellular adhesion, indicating a conformational change.
Conclusions:
- AQP0 transitions from a water channel in the cortex to an adhesion molecule in the core.
- Post-translational modification (cleavage) alters AQP0's function.
- This functional plasticity supports the gene sharing concept in crystallin evolution.