Single-channel permeability and glycerol affinity of human aquaglyceroporin AQP3

Publication date: Available online 17 January 2019Source: Biochimica et Biophysica Acta (BBA) - BiomembranesAuthor(s): Roberto A. Rodriguez, Huiyun Liang, Liao Y. Chen, Germán Plascencia-Villa, George PerryAbstractFor its fundamental relevance, transport of water and glycerol across the erythrocyte membrane has long been investigated before and after the discovery of aquaporins (AQPs), the membrane proteins responsible for water and glycerol transport. AQP1 is abundantly expressed in the human erythrocyte for maintaining its hydrohomeostasis where AQP3 is also expressed (at a level ~30-folds lower than AQP1) facilitating glycerol transport. This research is focused on two of the remaining questions: How permeable is AQP3 to water? What is the glycerol-AQP3 affinity under near-physiological conditions? Through atomistic modelling and large-scale simulations, we found that AQP3 is two to three times more permeable to water than AQP1 and that the glycerol-AQP3 affinity is approximately 500/M. Using these computed values along with the data from the latest literature on AQP1 and on erythrocyte proteomics, we estimated the water and glycerol transport rates across the membrane of an entire erythrocyte. We used these rates to predict the time courses of erythrocyte swelling-shrinking in response to inward and outward osmotic gradients. Experimentally, we monitored the time course of human erythrocytes when subject to an osmotic or glycerol gradient with light scattering in a stopp...

Source: Biochimica et Biophysica Acta (BBA) Biomembranes - January 17, 2019 Category: Biochemistry Source Type: research