Graduate Program Information
My Contact Information

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

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

Nogami K, Zhou Q, Myles T, Leung LL, Wakabayashi H, Fay PJ (2005) Exosite-interactive regions in the A1 and A2 domains of factor VIII facilitate thrombin-catalyzed cleavage of heavy chain. J Biol Chem, 280:18476-87

Ansong C, Fay PJ (2005) Factor VIII A3 Domain Residues 1954-1961 Represent an A1 Domain-Interactive Site. Biochemistry, 44:8850-7

Nogami K, Zhou Q, Wakabayashi H, Fay PJ (2005) Thrombin-catalyzed activation of factor VIII with His substituted for Arg372 at the P1 site. Blood, 105:4362-8

Fay PJ, Jenkins PV (2005) Mutating factor VIII: lessons from structure to function. Blood Rev, 19:15-27

Wakabayashi H, Su YC, Ahmad SS, Walsh PN, Fay PJ (2005) A Glu113Ala mutation within a factor VIII Ca2+-binding site enhances cofactor interactions in factor Xase. Biochemistry, 44:10298-304

Jenkins PV, Dill JL, Zhou Q, Fay PJ (2004) Contribution of factor VIIIa A2 and A3-C1-C2 subunits to the affinity for factor IXa in factor Xase. Biochemistry, 43:5094-101

Wakabayashi H, Freas J, Zhou Q, Fay PJ (2004) Residues 110-126 in the A1 domain of factor VIII contain a Ca2+ binding site required for cofactor activity. J Biol Chem, 279:12677-84

Fay PJ (2004) Activation of factor VIII and mechanisms of cofactor action. Blood Rev, 18:1-15

Jenkins PV, Dill JL, Zhou Q, Fay PJ (2004) Clustered basic residues within segment 484-510 of the factor VIIIa A2 subunit contribute to the catalytic efficiency for factor Xa generation. J Thromb Haemost, 2:452-8

Nogami K, Freas J, Manithody C, Wakabayashi H, Rezaie AR, Fay PJ (2004) Mechanisms of interactions of factor X and factor Xa with the acidic region in the factor VIII A1 domain. J Biol Chem, 279:33104-13

Nogami K, Lapan KA, Zhou Q, Wakabayashi H, Fay PJ (2004) Identification of a factor Xa-interactive site within residues 337-372 of the factor VIII heavy chain. J Biol Chem, 279:15763-71

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