Folia Biologica
Journal of Cellular and Molecular Biology, Charles University 

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Fol. Biol. 2006, 52, 173-180

https://doi.org/10.14712/fb2006052050173

Regulation of Selectivity and Translocation of Aquaporins: an Update

Miloš M. Petrović1, K. Valeš2, G. Stojan3, G. Basta-Jovanović3, D. M. Mitrović1

1Institute of Physiology, School of Medicine, Belgrade University, Serbia
2Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
3Institute of Pathology, School of Medicine, Belgrade University, Serbia

Received September 2006
Accepted October 2006

All living beings need to solve the problem of controlled transport of water. To this purpose, a special group of integral membrane proteins called aquaporins has evolved. There are 13 known members of this family that act as channels for water and small solutes, such as glycerol and urea. Although they allow large flux of water, they successfully prevent passage of protons. Here, we present the review of the data from the literature on the selectivity mechanism of aquaporins. The regulation of aquaporin activity occurs through regulation of expression of their genes, changing the localization of the already existing proteins in the cells and direct regulation of the activity in situ. We present the review of new data on the mechanisms of direct regulation. Special emphasis is on the advances in comprehension of aquaporin-2 translocation in collecting tubule cells of the kidney. Four elements of this process are described: 1) the role of protein kinase A and phosphorylation of serine 256 on aquaporin-2, 2) the transport of vesicles along the microtubules toward the apical membrane, 3), the removal of cytoskeletal subapical obstruction and the role of Rho GTPase and ezrin-radixin-moesin proteins in this, and 4) elevation of the cytosolic Ca2+ concentration, the fusion of the vesicle with the apical membrane and the role of SNARE proteins in exocytosis.

References

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