Dr. Weber studies the mechanism of action by which actin binding proteins regulate the assembly and disassembly of actin filaments. At the moment the laboratory is focusing on proteins that may be involved in length regulation of actin filaments in muscle and non-muscle cells. Two such proteins are tropomyosin, which polymerizes along the length of actin filaments and tropomodulin, a protein that caps the slowly reacting end of the actin filament in a complex manner.

Currently, the lab is working on three projects which attempt to answer the following questions:

1. Does the mechanism by which the energy of ATP hydrolysis is used in the action of tropomodulin, the pointed end capping protein, involve a change in the nucleotide content of the terminal actin molecules?
2. Where on tropomodulin is the binding site for actin?
3. Does the cooperation between tropomodulin and tropomyosin require that the two proteins are bound to each other?

1. Gregorio, C.C., Weber, A., Bondad, M., Pennise, C.R. and Fowler, V.M. (1995) Requirement of pointed-end capping by tropomodulin to maintain actin filament length in embryonic chick cardiac myocytes. Nature 376: 83-86.
2. Weber, A., Pennise, C.R., Babcock, G.G. and Fowler, V.M. (1994) Tropomodulin caps the pointed ends of actin filaments. J. Cell. Biol. 127: 1627-1635.
3. Weber, A., Pennise, C.R. and Pring, M. (1994) DNase I increases the rate constant of depolymerization at the pointed (-) end of actin filaments. Biochemistry 33: 4780-4786.
4. Pring, M., Weber, A. and Bubb, M.R. (1992) Profilin-actin complexes directly elongate actin filaments at the barbed end. Biochemistry 31: 1827-1836.
5. Weber, A., Nachmias, V.T., Pennise, C.R., Pring, M. and Safer, D. (1992) Interaction of thymosin 4 with muscle and platelet actin: implications for actin sequestration in resting platelets. Biochemistry 31: 6179-6185.