Abstract
FACILITATED diffusion of small organic molecules across cell membranes is thought to be carrier-mediated in part because the process displays reaction kinetics. Models describing carrier transport assume that the transported molecule is associated with the membrane, reacting presumably with membrane proteins, and is then moved across the barrier. Many models also assume that the transported molecule becomes soluble in a membrane lipid phase as a result of this interaction. This assumption precludes treatment of large hydrophilic molecules, such as globular proteins, in a similar fashion, because it is not likely that one, or even several interactions with membrane proteins, would make the whole molecule sufficiently hydrophobic to completely enter a lipid phase. Our experiments show that proteins do cross membranes individually and that transit appears to be reaction dependent.
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LIEBOW, C., ROTHMAN, S. Membrane Transport of Proteins. Nature New Biology 240, 176–178 (1972). https://doi.org/10.1038/newbio240176a0
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DOI: https://doi.org/10.1038/newbio240176a0
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