Modelo Del Mosaico Fluido (Articulo Original)

The Fluid Mosaic Model of the Structure of Cell Membranes Author(s): S. J. Singer and Garth L. Nicolson Source: Science, New Series, Vol. 175, No. 4023 (Feb. 18, 1972), pp. 720-731 Published by: American Association for the Advancement of Science Stable URL: http://www.jstor.org/stable/1733071 Accessed: 12/09/2008 12:57
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The Fluid Mosaic Model of the Structure of Cell Membranes
Cell membranes are viewed as two-dimensional solutions of oriented globular proteins and lipids.
S. J. Singer and Garth L. Nicolson

experimental evidence in terms of the model; and (v) to show that the fluid mosaic model suggests new ways of thinkingabout membranefunctions and membrane phenomena.
Thermodynamicsand Membrane Structure

Biological membranesplay a crucial role in almost all cellular phenomena, yet our understandingof the molecular organizationof membranesis still rudimentary.Experiencehas taughtus, however, that in order to achieve a satisfacof tory understanding how any biological system functions, the detailed molecularcomposition and structureof that system must be known. While we arestill a long way from such knowledge about membranesin general,progress at both the theoretical and experimentallevels in recentyearshas brought us to a stage where at least the gross aspects of the organizationof the proteins and lipids of membranes can be discerned.There are some investigators, however, who, impressedwith the great diversityof membranecompositionsand functions, do not think thereare any useful generalizationsto be made even about the gross structureof cell membranes. We do not share that view. We suggest that an analogy exists between the problems of the structureof membranes and the structure of proteins. The latter are tremendouslydiverse in composition, function, and detailed structure. Each kind of protein molecule is structurally unique. Nevertheless, generalizationsabout protein structure have been very useful in understanding the propertiesand functions of protein molecules. Similarly, valid generalizations may exist about the ways in which the proteins and lipids are organizedin an intact membrane.The ultimate test of such generalizations,or models, is whether they are useful to explain old experiments and suggest new ones. Singer (1) has recentlyexamined in
Dr. Singer is a professor of biology at the University of California at San Diego, La Jolla. Dr. Nicolson is a research associate at the Armand Hammer Cancer Center of the Salk Institute for Biological Studies, La Jolla, California. 720

considerable detail several models of the gross structural organization of membranes,in terms of the thermodynamics of macromolecularsystems and in the...