Using molecular dynamics (MD) simulations, we studied the structure and dynamics of two dimyristoylphosphatidylcholine (DMPC):cholesterol bilayers at concentrations representative of the ocular lens (ratios of 1:1 and 1:2). These MD simulations agree well with experimental deuterium order parameters and bilayer peak-to-peak distances. Although it is known that the average surface area per lipid rapidly decreases from low to moderate levels of cholesterol, our simulations indicate that there is a relatively small change in the average lipid area from 50 to 66.7% cholesterol (40.5 +/- 0.2 and 39.5 +/- 0.1 angstrom(2)/lipid, respectively). Radial distribution functions for the hydroxyl group on cholesterol indicate the formation of cholesterol-only nanoscale domains for the membrane with 66.7% cholesterol but a uniform distribution of cholesterol and DMPC for the membrane with 50% cholesterol. These small domains form a single shell of hexagonally packed cholesterols that are interconnected in a web-like structure of cholesterol. Calculations of internal DMPC dynamics show that the relaxation times for carbon hydrogen reorientation of choline decrease with an increase in cholesterol, but the main body (carbonyl-glycerol to C11) is independent of cholesterol concentration. MD simulations of the aquaporin 0 tetramer show stabilization in its interactions with lipid membranes containing cholesterol by forming ring ring stacking between surface aromatic residues of the protein and the rings of cholesterol. Moreover, there is an increase in hydrogen bonds with longer lifetimes in a mixed bilayer of DMPC and cholesterol.