title: F-Actin-depolymerizing activity of human serum.
abstract: Non-heated human and animal sera contain a factor which exhibited an inhibiting activity on the staining of actin-containing structures by anti-actin antibodies in indirect immunofluorescence experiments. The presence of this factor lowered the viscosity of F-actin preparations and caused, as studied by electron-microscopy, a depolymerization of F-actin filaments as well as inhibition of filament formation of G-actin. The factor was, after its reaction with F-actin, liberated seemingly unaffected, indicating an enzymatic activity. The factor tentatively termed 'F-actin depolymerizing factor' was heat-sensitive and trypsin sensitive but resisted reduction. It was Ca2+ dependent and the staining inhibiting reaction was faster at 30 degrees C and 37 degrees C than at lower temperatures. Gel filtration experiments on Sephadex G-200 suggested a molecular size of the actin depolymerizing factor slightly higher than that of albumin. The electrophoretic mobility was that of gamma 2 globulin. The physiological role of the factor might be to prevent the presence of F-actin filaments within the circulation.
mesh_terms: D000199:Actins / Q000032:analysis* / Q000097:blood; D000818:Animals; D000906:Antibodies; D005455:Fluorescent Antibody Technique; D006801:Humans; D006980:Hyperthyroidism / Q000378:metabolism; D007668:Kidney / Q000032:analysis; D008099:Liver / Q000032:analysis; D046911:Macromolecular Substances; D009132:Muscles / Q000032:analysis / Q000648:ultrastructure; D009928:Organ Specificity; D051381:Rats; D013270:Stomach / Q000032:analysis; D013961:Thyroid Gland / Q000032:analysis
chemical_list: D000199:Actins; D000906:Antibodies; D046911:Macromolecular Substances