From: Homology modeling of the cation binding sites of Na+K+-ATPase. Ogawa H, Toyoshima C. Proc Natl Acad Sci. 99(25): 15977?15982. 2002
http://www.pnas.org/content/99/25/15977/F4.large.jpg
Molecular geometry of sodium and potassium binding sites
From: Homology modeling of the cation binding sites of Na+K+-ATPase. Ogawa H, Toyoshima C. Proc Natl Acad Sci. 99(25): 15977?15982. 2002
http://www.pnas.org/content/99/25/15977/F4.large.jpg
Sodium pump animation
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html
From: Human Anatomy by McKinley and O'Laughlin
ATP phosphorylation reaction 
From: Essential Cell Biology by Garland (2004)
http://www.accessexcellence.org/RC/VL/GG/ecb/ecb_images/03_32_ATP_and_ADP_cycle.jpg