title: Fibronectin potentiates actin polymerization in thrombin-activated platelets.
abstract: The effect of fibronectin on the polymerization state of actin was studied. Triton X-100-insoluble cytoskeleton was prepared from thrombin-activated platelets, and the conversion of G-actin into F-actin was monitored by an assay involving DNase I inhibition by G-actin. It was found that fibronectin bound to membrane receptors decreased the level of platelet G-actin. This observation suggests that in the presence of fibronectin a larger amount of F-actin becomes incorporated into the Triton X-100-insoluble cytoskeleton. At the same molar concentration, fibrinogen only slightly increased actin polymerization, whereas bovine serum albumin at a much higher concentration caused a small inhibition of actin immobilization. Our data show that fibronectin, through interaction with the platelet actomyosin fibrillar system, facilitates actin polymerization into the cytoskeleton.
mesh_terms: D000199:Actins / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003571:Cytochalasin B / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000037:antagonists & inhibitors; D004357:Drug Synergism; D005353:Fibronectins / Q000494:pharmacology*; D006801:Humans; D007158:Immunologic Techniques; D046911:Macromolecular Substances; D013917:Thrombin / Q000494:pharmacology*
chemical_list: D000199:Actins; D005353:Fibronectins; D046911:Macromolecular Substances; D003571:Cytochalasin B; D003850:Deoxyribonuclease I; D013917:Thrombin