Robert W. Mercer, Ph.D. Professor Cell Biology and Physiology Molecular Cell Biology Program Computational and Molecular Biophysics Program
Office Phone: 314-362-6924 Lab Phone: 314-362-6922 Other Phone: FAX: 314-362-7463 Box: 8228 Lab Address: 5512 Cancer Research Building Email: rmercer@wustl.edu Website: http://www.cellbio.wustl.edu/FACULTY/Mercer.htm Keywords: cell membrane; development; Na K-ATPase; excitable tissue; cell volume Short Research Description: Molecular and cell biology of ion pumps and transporters in plasma membrane; cell polarity.
Research Abstract: The Na,K-ATPase or sodium pump is a heterodimeric membrane protein that is responsible for maintaining the high internal potassium and low internal sodium concentrations characteristic of most animal cells. This enzyme couples the hydrolysis of ATP to the movement of sodium and potassium ions across the plasma membrane, thus producing the electrochemical gradients that are the primary source of energy for the active transport of nutrients, the action potential of excitable tissues, and the regulation of cell volume and pH. The Na,K-ATPase consists of at least two noncovalently linked subunits: a 100 kDa multi-spanning membrane protein termed the a subunit, and the b subunit, a smaller glycosylated membrane protein. Multiple isoforms for both the a (a1-a4) and b (b1-b3) subunits have been identified. These isoforms exhibit a tissue-specific and developmental pattern of expression that may be important in the maintenance and regulation of Na,K-ATPase activity. We have also isolated and characterized the cDNAs for the g-subunit, a small hydrophobic protein associated with the other subunits. Research in this laboratory is presently directed at using the methods of molecular biology to study the structure, function, and regulation of this important enzyme.
Selected Publications: Sha Q, Lansbery KL, Distefano D, et al. Heterologous expression of the Na,K-ATPase g subunit in Xenopus oocytes induces an endogenous, voltage-gated large diameter pore. J Physiol 2001 535:407-417. Habiba A, Blanco G, Sánchez G, Mercer RW. Expression, activity and distribution of Na,K-ATPase subunits during in vitro neuronal induction. Brain Res 2000 875:1-13. Blanco G, Melton RJ, Sánchez G, et al. Functional characterization of a testes-specific a subunit isoform of the Na,K-ATPase. Biochemistry 1999 38:13661-13669. Blanco G, Mercer RW. Isozymes of the Na,K-ATPase: Heterogeneity in structure, diversity in function. Am J Physiol 1998 257:F633-F650. Minor NT, Sha Q, Nichols CG, et al. The g-subunit of the Na,K-ATPase induces cation channel activity. Proc Natl Acad Sci USA 1998 95:6521-6525.