A membrane cytoskeleton from Dictyostelium discoideum. I. Identification and partial characterization of an actin-binding activityWomen’s Health Research Faculty Publications
UMMS AffiliationDepartment of Cell Biology
SubjectsActins; Cell Membrane; Dictyostelium; Membrane Lipids; Membrane Proteins; Polyethylene Glycols; Viscosity
AbstractDictyostelium discoideum plasma membranes isolated by each of three procedures bind F-actin. The interactions between these membranes and actin are examined by a novel application of falling ball viscometry. Treating the membranes as multivalent actin-binding particles analogous to divalent actin-gelation factors, we observe large increases in viscosity (actin cross-linking) when membranes of depleted actin and myosin are incubated with rabbit skeletal muscle F-actin. Pre-extraction of peripheral membrane proteins with chaotropes or the inclusion of Triton X-100 during the assay does not appreciably diminish this actin cross-linking activity. Lipid vesicles, heat-denatured membranes, proteolyzed membranes, or membranes containing endogenous actin show minimal actin cross-linking activity. Heat-denatured, but not proteolyzed, membranes regain activity when assayed in the presence of Triton X-100. Thus, integral membrane proteins appear to be responsible for some or all of the actin cross-linking activity of D. discoideum membranes. In the absence of MgATP, Triton X-100 extraction of isolated D. discoideum membranes results in a Triton-insoluble residue composed of actin, myosin, and associated membrane proteins. The inclusion of MgATP before and during Triton extraction greatly diminishes the amount of protein in the Triton-insoluble residue without appreciably altering its composition. Our results suggest the existence of a protein complex stabilized by actin and/or myosin (membrane cytoskeleton) associated with the D. discoideum plasma membrane.
Rights and PermissionsCitation: J Cell Biol. 1981 Feb;88(2):396-409. Link to article on publisher's website
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Citation InformationElizabeth J. Luna, V. M. Fowler, J. Swanson, D. Branton, et al.. "A membrane cytoskeleton from Dictyostelium discoideum. I. Identification and partial characterization of an actin-binding activity" Vol. 88 Iss. 2 (1981) ISSN: 0021-9525 (Print)
Available at: http://works.bepress.com/lunae/24/