UMMS Affiliation

Department of Cell Biology



Document Type



Actins; Adenosine Triphosphate; Binding, Competitive; Cell Membrane; Cytoskeleton; Dictyostelium; Electrophoresis, Polyacrylamide Gel; Kinetics; Membrane Proteins; Microscopy, Electron; Myosin Subfragments; Myosins; Peptide Fragments


Cell Biology | Life Sciences | Medicine and Health Sciences


The binding between sonicated Dictyostelium discoideum plasma membrane fragments and F-actin on Sephacryl S-1000 beads was found to be competitively inhibited by myosin subfragment-1. This inhibition is MgATP-sensitive, exhibits a Ki of approximately 5 X 10(-8) M, and is reciprocal, since membranes inhibit the binding of 125I-heavy meromyosin to F-actin on beads. These experiments demonstrate that membrane binding and S-1 binding to F-actin on beads are mutually exclusive and, therefore, that the membrane fragments bind predominantly to the sides, rather than to the ends, of the actin filaments. This conclusion is supported by electron micrographs that show many lateral associations between membrane fragments and bead-associated actin filaments. Such lateral associations could play an important role in the organization and lateral movement of membrane proteins by the cytomusculature.

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Citation: J Cell Biol. 1984 Jul;99(1 Pt 1):71-8. Link to article on publisher's website

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