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Aquaporin-CHIP-related protein in frog urinary bladder: localization by confocal microscopy
G Calamita1, M G Mola, P Gounon
1Istituto di Fisiologia Generale, Università degli studi di Bari, Italy.
The Journal of Membrane Biology
|February 1, 1995
Summary
Aquaporin CHIP-like proteins are present in the urinary bladder epithelium but do not appear to insert into the apical membrane during the antidiuretic response. Further research is needed to identify the specific protein and its function.
Area of Science:
- Cell Biology
- Physiology
- Biochemistry
Background:
- Aquaporin CHIP (28 kDa) is a proposed water channel in erythrocytes and kidney proximal tubules.
- Previous work identified a 30 kDa CHIP28-like protein in frog urinary bladder epithelium.
- The cellular localization of these CHIP28-like proteins in the urinary bladder was investigated.
Purpose of the Study:
- To determine the cellular and subcellular localization of CHIP28-like proteins in the urinary epithelium.
- To investigate whether these proteins are inserted into the apical membrane during the antidiuretic response.
Main Methods:
- Confocal fluorescence microscopy was employed to visualize CHIP28-like proteins.
- Triton X-100 permeabilization was used to access intracellular and membrane-bound proteins.
- Antibody specificity was confirmed by pre-adsorption assays.
Main Results:
- CHIP28-like proteins were clearly labeled at the apical border of the urinary epithelium after permeabilization.
- Labeling was distributed throughout the apical domain and at the cellular contour in deeper sections.
- No differences in labeling patterns were observed between resting and ADH-treated bladders.
Conclusions:
- CHIP-like proteins are present in the urinary bladder epithelium but do not appear to be inserted into the apical membrane during the antidiuretic response.
- The identity of the labeled protein (CHIP28 or a related protein) remains to be confirmed.
