1. Basic Science Review A Tale of Three Proteins by Jack B. Alperin, MD, FACP

2. The Proteins Are… Von Willebrand Factor Factor VIII ADAMTS 13

3. von Willebrand Factor Gene Location Chr. 12p 12.2 - 12.3 Synthetic Site Endothelium Mol. Weight 0.5 - 20 MD Function Essential for both 1 st and 2 nd hemostasis

4. Factor VIII Gene LocationChr. Xq28 Cellular OriginHepatic sinusoidal endothelial cells Mol. WeightL 80 KD, H 90 - 200 KD FunctionCoag. cascade leading to a stable fibrin thrombus

5. ADAMTS 13* Gene LocationChr. 9q 34 Cellular OriginHepatic stellate cells Mol. Weight150 KD FunctionVWF proteinase splits the amino bond at … -842(Tyr) - 843(Meth)- *a disintegrin and metalloproteinase with thrombospondin 1 motif 13

6. von Willebrand Factor Role in Primary Hemostasis Platelet adhesion to collagen at sites of vascular injury Platelet aggregation at sites of vascular injury Role in Secondary Hemostasis Binds and stabilizes factor VIII in plasma Transports factor VIII to sites of vascular injury

7. von Willebrand Factor Monomer NH 2 -SER-ARG-VAL-LYS-GLY-GLU-ARG-GLY-ASP-SER-LYS-COOH 1 272 449 728 911 1365 1744 1747 2050 Factor VIIIGPIb Collagen GPIIb/IIIa

8. Polymerization of VWF ER N C S S  Dimer Golgi N C S S S S S S  Multimer

9. Definitions VWF:RCo A property of VWF that supports ristocetin- induced aggregation of normal platelets. Commonly called ristocetin cofactor activity. VWF Multimer Analysis Multimers of different molecular weights found in plasma by chromatography and electrophoresis. VWF:Ag An antigenic determinant on the VWF measured by an immunoassay using a heterologous or monoclonal antibody.

10. 1.Normal 2.VWD Type 1 3.VWD Type 2a 4.Normal

12. X-Chromosome Sinusoidal Liver Cells (2332 aa) F.VIII precursor *(variable) F.VIII molecule Chromosome 12 Endothelial Cells Megakaryocytes Pre-Pro-VWF (2813 aa) VWF monomer (2050 aa) VWF multimer (0.5-20 x10 6 K) (F.VIII) – (VWF) Complex * light chain 80 x 10 3 D heavy chain90-200 x 10 3 D

19. 1 ULVWF 2 VWFCP VWF multimers ENDOTHELIAL CELL 1.Ultra Large von Willebrand Factor Multimers 2.von Willebrand Factor Cleaving Proteinase or ADAMTS 13

23. von Willebrand Factor Cleaving Proteinase (ADAMTS13) Absent in inherited TTP Inhibited by antibodies in acquired TTP Recombinant form may be used to treat TTP Destroys specific VWF mutations causing some forms of VWD Type 1 and Type 2a Variant may be a risk factor for myocardial infarction

24. The von Willebrand Factor Cleaving Proteinase (ADAMTS13)* Gene location - Chr. 9q34, 29 exons Synthesis - Stellate Cells in Liver Structure – 1427 aa, Mr 150 KDHalf-life 2-4 Days Splits the amino bond between-842 (Tyr)  -  843 (Meth)- Most effective when substrate (VWF) is denatured by shear stress *ADAMTS 13 - (a disintegrin and metalloproteinase with thrombospodin 1 motif 13)