title: Binding and degradation of blood coagulation factor XIII by cultured fibroblasts.
abstract: The interaction of Factor XIII with cultured fibroblasts was examined using 125I-labeled protein and immunofluorescence. Platelet or plasma Factor XIII bound to confluent cell layers. Binding reached an apparent steady state after 8 h. Activation with thrombin increased the binding of both the platelet and plasma forms of the enzyme. After a 1-2 h lag, a chloroquine-inhibitable increase in trichloroacetic acid-soluble radioactivity was detected in the medium. Gel electrophoresis in sodium dodecyl sulfate indicated that approximately 16-fold more a subunit (catalytic) of 125I-plasma Factor XIII bound to the cell layer than b subunit (carrier) and that some large complexes containing Factor XIII were formed with the cell layer. Factor XIII binding increased linearly with concentrations of Factor XIII up to 230 micrograms/ml, whereas a component of the degradation of Factor XIII was saturable at about 20 micrograms/ml. Factor XIII associated with cell layers was catalytically active since it could cross-link fibronectin. By immunofluorescence the a subunit of Factor XIII was localized to fibronectin-containing extracellular fibrils and, in the presence of chloroquine, to intracellular granules. These results indicate that the a subunit of Factor XIII binds to the fibroblast extracellular matrix and matrix assembly sites, where it remains active, and to a putative cell-surface receptor which mediates its internalization and degradation.
authors.affiliation: Department of Physiological Chemistry and Medicine, University of Wisconsin, Madison 53706.
authors.forename: E L
authors.initials: EL
authors.lastname: Barry
authors.forename: D F
authors.initials: DF
authors.lastname: Mosher
mesh_terms: D001792:Blood Platelets / Q000032:analysis; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology; D003840:Deoxycholic Acid; D004220:Disulfides / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005176:Factor XIII / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D012995:Solubility; D013917:Thrombin / Q000494:pharmacology; D011503:Transglutaminases / Q000378:metabolism
chemical_list: D004220:Disulfides; D046911:Macromolecular Substances; D003840:Deoxycholic Acid; D002738:Chloroquine; D005176:Factor XIII; D011503:Transglutaminases; D013917:Thrombin