title: Water permeability in human erythrocytes: identification of membrane proteins involved in water transport.
abstract: The water permeability of human erythrocytes has been monitored by nuclear magnetic resonance (NMR) before and after treatment of the cells with various sulfhydryl reagents. Preincubation of the cells with N-ethylmaleimide (NEM), a non-inhibitory sulfhydryl reagent, results in a faster and more sensitive inhibition of water exchange by mercurials. The inhibition of water exchange by p-chloromercuribenzene sulfonate (PCMBS) was maximal at a binding of approximately 10 nmol PCMBS per mg protein when non-specific sulfhydryl groups are blocked by NEM. Inhibition by PCMBS has been correlated with the binding of 203Hg to erythrocyte membrane proteins. A significant binding of label to band 3 and the polypeptides in band 4.5 occurs, with approximately 1 mol of mercurial bound per mol of protein. Inhibition of water transport by sulfhydryl reagents does not induce major morphological changes in the cells as assessed by freeze-fracture and scanning electron microscopy.
mesh_terms: D002731:4-Chloromercuribenzenesulfonate / Q000097:blood; D001692:Biological Transport; D002463:Cell Membrane Permeability; D004058:Diffusion; D004910:Erythrocyte Membrane / Q000378:metabolism* / Q000648:ultrastructure; D004912:Erythrocytes / Q000378:metabolism*; D005613:Freeze Etching; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning
chemical_list: D002731:4-Chloromercuribenzenesulfonate