<prompt> Rapid diffusion of water across cell membranes depends on the presence of water channels, called aquaporins. Proximal convoluted tubule have:Aquaporin 1Aquaporin 2Aquaporin 5Aquaporin 9  <response>: Aquaporin-1 is localized to both the basolateral and apical membrane of the proximal tubules and its presence allows water to move rapidly out of the tubule along the osmotic gradients set up by active transpo of solutes, and isotonicity is maintained. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. 2012. Chapter 37. Renal Function Micturition. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks Eds, Ganongs Review of Medical Physiology, 24e. 