Radmila Sarac, Ph.D.
Office: Gyte 290
Telephone: (219) 989-2492
Ph.D. Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, IL
B.S. Pharmacy, Purdue University, West Lafayette, IN
My primary research interests include understanding the functional and structural properties of the G protein-activated inwardly rectifying potassium ion channel (GIRK) family. GIRK channels mediate electrophysiological signals in the cell in addition to coupling to other biochemical signaling complexes. Inwardly rectifying potassium channels form heteromeric and homomeric channels, which are capable of assembly within a subfamily or less frequently, between subfamilies. GIRK subunits are differentially expressed and specific subunits have been shown to mediate diverse roles of channel targeting and expression. Utilizing multiple experimental methods to analyze protein expression, localization, and channel function, I have examined how different subunits of the GIRK channel contribute to functional properties, and specifically, which protein residues are involved in the activation and function of the assembled channel. Analysis of the specific mechanism of channel function is dependent upon not only the molecular composition of the channel, but also the diversity of expression, trafficking and interactions of the various subunits. For many proteins, specific molecular sequences have been identified that mediate interactions between proteins as well as the modification and targeting of the protein to the appropriate cellular environment, whether this results in export out of the ER or expression at the plasma membrane. Understanding how different GIRK subunits interact and dictate channel formation and localization will provide useful information when examining functional output of various systems coupled to the channel. The elucidation of channel function at a molecular level provides further information about protein and cellular mechanisms that mediate responses and contribute to a specific physiological role as well as possible roles in disease states. In addition, crystallization of various bacterial potassium channels has provided a basis of scientific knowledge in which to explore the relationship between protein architecture and possible contributions to function. We are also interested in developing educational cell biology learning modules that integrate these structures and innovations in 3D active learning.
(Abstracts are linked to authors name, please click to view.)
Deriy, L., Wang, Gomez, E., Sarac, R., Zhang, D., and Nelson, D. J. 2009. Synaptic chloride channel ClC-3 is regulated by Ca/CaM-dependent phosphorylation/ dephosphorylation, Program No. 821.16/C65. 2009 Neuroscience Meeting Planner, Chicago, IL: Society of Neuroscience, 2009. Online.
Gomez, E., Hipp, J. and Sarac R. (2009) Analysis of GIRK subunit domain association and channel function. 2009. Biophysical Society Meeting Abstracts. Biophysical Journal, Supplement, Vol.96:3, Abstract, Pos-B367.
Deriy, L., Wang X., Zheng, D., Sarac R., and Nelson D. 2008. Ca/CaM- dependent phosphorylation/dephosphorylation regulates chloride channel ClC-3 at the synapse and determines synaptic strength. 2008 Biophysical Discussions: Calmodulin modulation of Ion Channels, Study Book, Part 2 . Asilomar Conference October 30 – November 2008.
Chakrabarty T., Kambesis, N., Nelson D.J., and Sarac R. 2006. Investigating hydrophobic domain interactions in G-protein coupled inwardly rectifying potassium channels (GIRK) using FRET microscropy. February 2006. Abstract. 50th Annual Biophysical Society Meeting, http://www.abstractsonline.com/viewer/SearchResults.asp
Sarac R, Hou P, Hurley, KM, Hriciste D, Cohen, N.A., and Nelson DJ. 2005. Mutation of critical GIRK subunit residues disrupts N and C termini association and channel function. J. Neuroscience 25(7):1836-1846.
Drum CL, Yan S-Z, Sarac R, Mabuchi Y, Beckingham K, Bohm A, Grabarek Z, Tang W-J. 2000. An Extended Conformation of Calmodulin Induces Interactions between the Structural Domains of Adenylyl Cyclase form Bacillus anthracis to Promote Catalysis. The Journal of Biological Chemistry 275(46):36334-363 40.
Keshvara LM, Isaacson CC, Yankee TM, Sarac R, Harrison ML, and Geahlen RL. 1998. Syk- and Lyn-Dependent Phosphorylation of Syk on Multiple Tyrosines Following B Cell Activation includes a Site that Negatively Regulates Signaling. The Journal of Immunology 161:5276-5283.
BIOL 10100 – Introductory Biology
BIOL 21400 – Anatomy and Physiology II
BIOL 35700 – Intro to Animal Physiology
BIOL 41800 – Drugs and Disease
BIOL 59500 – Advanced Cell Biology
BIOL 59500 – Ion Channel Research (directed student research)
BIOL 59500 – Ion Channel Readings
BIOL 69800 – Research MS Thesis