Biochemistry: protein chemical studies of membrane-bound proteins catalyzing the transport of ions and of the active site of ribonucleotide reductase
Office: Urey Hall Addn 3050H
Awards and Academic Honors
Editorial Board Biochemistry
NIH Career Development Award
Damon Runyon Postdoctoral Fellow, University of California, San Diego
Phi Beta Kappa; National Science Foundation Predoctoral Fellow, Harvard
In our laboratory we are studying the structure and function of three proteins found in the plasma membranes of animal cells: Na+/K+-transporting ATPase, acetylcholine receptor, and anion carrier, and an enzyme found in the cytoplasm of all living cells, ribonucleotide reductase. Na+/K+-Transporting ATPase is responsible for the primary active transport of sodium and potassium ions across the plasma membrane of animal cells. It catalyzes this process by spanning the membrane and forming a compartment through which the cations pass. The segments of the sequence of the protein that form this compartment are those that span the bilayer. Acetylcholine receptor transforms the neural action potential into a muscular action potential at the synapse. Anion carrier is responsible for the bicarbonate transport across the plasma membrane of the erythrocyte that permits the efficient transfer of bicarbonate from peripheral tissues to the lungs. Because each of these latter two proteins also catalyze the transport of ions, each should also have a compartment formed by the membrane-spanning segments of the protein through ions. We are using immunochemistry and protein chemistry to identify the segments of each of these three proteins that span the membrane to form the respective compartments for the transported ions. We are also examining cysteines within the active site of ribonucleotide reductase. It has been proposed that during the chemical reaction catalyzed by this enzyme, these cysteines either become free radicals or combine with each other to form cystines. These transformations are thought to be central to the conversion of ribonucleotides into deoxyribonucleotides performed by this enzyme. The rates at which and the sequence in which these transformations occur will be examined by rapidly mixing the enzyme with a ribonucleotide and quenching the reaction at short times. The protein in each of these quenched samples will be cut into peptides and specific peptides will be isolated bt specific immunoadsorbents to assess the status of each of the cysteines in each of the samples.
Primary Research Area
- Activation of Epidermal Growth Factor Receptor by Epidermal Growth Factor. With J. Miller. Biochemistry 35, 5705 (1996).
- Topological Disposition of Tyrosine 486 in Anion Carrier from Human Erythrocytes. With M. Kalo. Biochemistry 35, 999 (1996).
- Mechanism in Protein Chemistry. Garland Publishing, New York (1995).
- Topological Disposition of Lysine 943 in Native Na+/K+-Transporting ATPase. With S. Anderberg. Biochemistry 34, 9058 (1995).
- Extracytoplasmic Disposition of Lysine b165 of Acetylcholine Receptor. Biochemistry. With K. Ewalt. Biochemistry 33, 5077 (1994).