Diacylglycerol in large alpha-actinin/actin complexes and in the cytoskeleton of activated platelets.
The interaction of the cytoskeleton with plasma membranes may be mediated by vinculin, alpha-actinin and other proteins; alpha-actinin can interact specifically with model membranes only if they contain diacylglycerol and palmitic acid. On stimulation of platelets by thrombin, which leads to a reorganization of the cytoskeleton, diacylglycerol is produced rapidly, simultaneously with the disappearance of phosphatidylinositol. One important function of the diacylglycerol produced in platelets may be the activation of the Ca2+-and phospholipid-dependent protein kinase C. We show here that, in the presence of diacylglycerol and palmitic acid, a supramolecular complex between alpha-actinin and actin is formed in vitro. In the electron microscope, this complex displays substructures similar to those of microfilament bundles in vivo. Furthermore, such alpha-actinin/lipid complexes can also be formed in situ during the stimulation of blood platelet aggregation. Thus, alpha-actinin may be one of the proteins directly involved in structures connecting the cytoskeleton to cell membranes.
D000185:Actinin / Q000502:physiology*; D000199:Actins / Q000502:physiology*; D001792:Blood Platelets / Q000648:ultrastructure*; D002462:Cell Membrane / Q000502:physiology; D003599:Cytoskeleton / Q000502:physiology*; D004075:Diglycerides / Q000502:physiology*; D005989:Glycerides / Q000502:physiology*; D006801:Humans; D046911:Macromolecular Substances; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000502:physiology; D010974:Platelet Aggregation
D000199:Actins; D004075:Diglycerides; D005989:Glycerides; D046911:Macromolecular Substances; D010169:Palmitic Acids; D000185:Actinin; D019308:Palmitic Acid