Graduate Program Information
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Professor of Biochemistry and Biophysics
Ph.D. University of Rochester 1982

Factor VIII serves as a protein cofactor for the serine protease, factor IXa in the surface-dependent conversion of factor X to factor Xa during the blood coagulation cascade reactions. Deficiency or defects in factor VIII result in hemophilia A, the most common of the severe, inherited bleeding disorders. Ongoing studies in our laboratory include physical and biochemical analyses of factor VIII structure and inter-subunit interactions. We are particularly interested in study of the activated form of the cofactor, factor VIIIa, which consists of a labile heterotrimeric structure. Additional studies assess functional changes reflecting altered structure following interaction of factor VIII/factor VIIIa with effector molecules (serine proteases) such as thrombin and activated protein C.

The role of factor VIIIa is to increase the k_cat of factor IXa by several orders of magnitude. Little is known about the mechanism by which this is achieved. A second major focus of our lab is to elucidate the molecular basis for the cofactor effect following reconstitution of the intrinsic factor Xase complex (factor IXa, factor VIIIa (or isolated subunits) plus phospholipid vesicles) using purified components.

These projects are complemented by the generation and analysis of recombinant proteins possessing point mutations at sites proposed to contribute to intra- and inter-protein interactions. Overall, our research program is aimed at gaining fundamental insights into the structure, activity and regulation of a protein central to hemostasis.

The Intrinsic Factor Xase enzyme complex. Factor VIIIa (left) and factor IXa (right) are shown associated with a phospholipid membrane. Proteins are drawn in ribbon format based upon the 5-domain model of factor VIII and the crystal structure of factor IX. The yellow balls show residues of the catalytic triad. The 558-loop in the factor VIIIa A2 domain and the 330-helix in the factor IXa protease domain are shown in red and blue, respectively. From Fay. Blood Rev. 18:1-15, 2004.

Recent Publications

Wakabayashi H, Griffiths AE, Fay PJ (2009) Combining mutations of charged residues at the A2 domain interface enhances factor VIII stability over single point mutations. J Thromb Haemost, 7:438-44

Newell JL, Fay PJ (2009) Cleavage at Arg1689 influences heavy chain cleavages during thrombin-catalyzed activation of factor VIII. J Biol Chem,

Wakabayashi H, Varfaj F, Deangelis J, Fay PJ (2008) Generation of enhanced stability factor VIII variants by replacement of charged residues at the A2 domain interface. Blood, 112:2761-9

Newell JL, Fay PJ (2008) Acidic residues C-terminal to the A2 domain facilitate thrombin-catalyzed activation of factor VIII. Biochemistry, 47:8786-95

Wakabayashi H, Fay PJ (2008) Identification of Residues Contributing to A2 Domain-dependent Structural Stability in Factor VIII and Factor VIIIa. J Biol Chem, 283:11645-51

Varfaj F, Wakabayashi H, Fay PJ (2007) Residues surrounding Arg336 and Arg562 contribute to the disparate rates of proteolysis of factor VIIIa catalyzed by activated protein C. J Biol Chem,

Wakabayashi H, Zhou Q, Varfaj F, Fay PJ (2007) A3 domain residue Glu1829 contributes to A2 subunit retention in factor VIIIa. J Thromb Haemost, 5:996-1001

Varfaj F, Wakabayashi H, Fay PJ (2007) Residues surrounding Arg336 and Arg562 contribute to the disparate rates of proteolysis of factor VIIIa catalyzed by activated protein C. J Biol Chem, 282:20264-72

Newell JL, Fay PJ (2007) Proteolysis at Arg740 facilitates subsequent bond cleavages during thrombin-catalyzed activation of factor VIII. J Biol Chem, 282:25367-75

Varfaj F, Neuberg J, Jenkins PV, Wakabayashi H, Fay PJ (2006) Role of P1 residues Arg336 and Arg562 in the activated-Protein-C-catalysed inactivation of Factor VIIIa. Biochem J, 396:355-62

Wakabayashi H, Zhou Q, Nogami K, Ansong C, Varfaj F, Miles S, Fay PJ (2006) pH-dependent association of factor VIII chains: enhancement of affinity at physiological pH by Cu2+. Biochim Biophys Acta, 1764:1094-101

Fay PJ (2006) Factor VIII structure and function. Int J Hematol, 83:103-8

Ansong C, Miles SM, Fay PJ (2006) Epitope mapping factor VIII A2 domain by affinity-directed mass spectrometry: residues 497-510 and 584-593 comprise a discontinuous epitope for the monoclonal antibody R8B12. J Thromb Haemost, 4:842-7

Graduate students in my laboratory work toward a Ph.D. degree in the following program[s]:

Ph.D. in Biochemistry

Ph.D. candidates in my laboratory may also be affiliated with these programs:

Contact Information

E-Mail: Philip_Fay@urmc.rochester.edu

Philip J. Fay
Department of Biochemistry and Biophysics
University of Rochester School of Medicine and Dentistry
601 Elmwood Ave, Box 712
Rochester, New York 14642

Office: Medical Center 3-8191
Telephone: (585) 275-6576; Fax: (585) 473-4314