Characterization of factor VIII related protein synthesized by human endothelial cell: a study of structure and function.
Crossed immunoelectrophoresis showed that factor VIII related protein (VIII R) synthesized in the human endothelial cell (EC-VIII R) had faster electrophoretic mobility than that secreted into the culture medium (MED-VIII R). Sodium dodecyl sulphate agarose gel electrophoresis followed by radioimmunofixation showed that EC-VIII R consisted of molecules varying from 0.26 x 10(6) to 3.76 x 10(6) daltons while MED-VIII R had molecules ranging from 0.93 x 10(6) to greater than 10 x (10)6 daltons, similar to that present in plasma. The smallest VIII R molecule present in normal plasma or spent culture medium (0.93 x 10(6) daltons) corresponded to a tetramer of subunits of 0.22-0.24 x 10(6) daltons. Only molecular forms greater than 3.76 x 10(6) daltons possessed ristocetin cofactor activity. Sonication (15 mu amplitude for 30 secs) effectively broke the non-covalent bonds of the VIII R multimers resulting in smaller molecules. Thus endothelial cells in culture synthesized VIII R subunits and assembled them into the higher multimeric forms on secretion. Different types of von Willebrand disease could result from defects of either of the two processes.
D000941:Antigens / Q000032:analysis; D003450:Cryoglobulins / Q000032:analysis; D004727:Endothelium / Q000166:cytology / Q000378:metabolism; D005169:Factor VIII / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D008970:Molecular Weight; D012310:Ristocetin / Q000378:metabolism; D013010:Sonication; D014841:von Willebrand Factor
D000941:Antigens; D003450:Cryoglobulins; D014841:von Willebrand Factor; D012310:Ristocetin; D005169:Factor VIII