期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：5
页码：1339-1343
DOI：10.1073/pnas.70.5.1339
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Although hydrophilic pores have been inferred to account for characteristics of the movement of water molecules across erythrocyte membranes, no direct evidence has associated such pores with actual structural differentiations within the membrane. Freeze-fracture and freeze-etch studies of isolated erythrocyte membranes show that they are comprised of fluid bilayer domains tranversed by protein-containing intercalations ("membrane intercalated particles"). It has previously been hypothesized that the topology of the polar and apolar spaces of the membrane-intercalated particles was not concentric the hydrophobic spaces being equatorially distributed. In consequence, axial organization of the hydrophilic regions could result in hydrophilic continuity across the membrane and might provide a structural basis for passage of hydrophilic molecules. The present experiments support this hypothesis. It is shown that sublimation at -100{degrees} of erythrocyte membrane suspensions (that had been incubated at pH 5.5 to cause aggregation of the membrane particles) results in progressive and selective sinking of the membrane regions comprised of aggregates of intercalated particles, i.e., that sublimation of water molecules occurs preferentially across these membrane regions. These results indicate that, under these experimental conditions, the membrane-intercalated particles provide a preferential structural pathway for passage of water molecules across erythrocyte ghost membranes.
关键词：membrane proteins ; transport ; membrane structure ; pore ; electron microscopy
