Administration and Staff

Stephen Sprang

Stephen Sprang

Professor, DBS & Associate Director, CBSD

Phone: 406-243-6028
Fax: 406-243-6024
Office: ISB 218
Personal Website

Current Position

Director, Center for Biomolecular Structure and Dynamics

Professor, Division of Biological Science

Associated Faculty Member, Department of Chemistry


 B.S. in Biochemistry from California State University of Los Angeles in 1971

Ph.D. in Biochemistry from the University of Wisconsin, Madison in 1977

Postdoctoral studies with Robert Fletterick at the University of Alberta and the University of California at San Francisco, 1978-1983

Research Interests

 Current work focusses on mechanisms of G protein activation by an intracellular guanine nucleotide exchange factor called Ric-8A. This protein appears to carry out multiple functions in cells: it is essential for asymmetric cell division and abscission, regulates neurotransmitter secretion and assists in the biogenesis of G protein alpha subunits, in addition to its role as a G protein activator. Ric-8A functions as a guanine nucleotide exchange factor by catalyzing the release of GDP from G alpha subunits. Ric-8A forms a nucleotide-free complex with G alpha, which dissociates only in the presence of GTP, leading to the formation of active GTP-bound alpha. In this regard, Ric-8A is functionally analogous to the well-characterized family of trans-membrane G Protein-Coupled Receptors (GPCR), which, upon agonist binding, catalyze nucleotide exchange from G protein heterotrimers.

We have shown that Ric-8A catalyzes nucleotide exchange by inducing large conformational changes within G alpha, possibly by inducing local unfolding at the nucleotide binding site and in surrounding elements of secondary structure. In analogy to the action of GPCRs, Ric-8A also induces separation of the two major domains of G alpha. We have employed a variety of biophysical methods to characterize Ric-8A-induced structural changes in G alpha, including scanning calorimetry, Double Electron-Electron spectroscopy (in collaboration with Wayne Hubbell's laboratory at UCLA), Hydrogen-Deuterium Mass Spectrometry (in collaboration with Brian Bothner's group at Montana State University), single-molecule fluorescence spectroscopy (with Sandy Ross at UM), and most recently using camelid nanobodies as functional and structural probes (in collaboration with Jan Staeyert's laboratory at VIB, the Netherlands). We make extensive use of site-directed mutagenesis, in conjunction with enzymological methods to understand the mechanism of Ric-8A action. Our laboratory studies other aspects of G protein function, as described in our publications, as well as the mechanism of adenylyl cyclase regulation.

Our work is funded by grants from the National Institutes of Health (R01GM105993)


We are among the research laboratories of the Center for Biomolecular Structure and Dynamics. We study the structural chemistry of cellular signal transduction - the protein machines that control the timing and rate of processes such as cell division, gene transcription, electrical conduction and mobilization of energy sources in cells. Much of our work has been focused on heterotrimeric G proteins, the ways that they are stimulated and repressed, and how they activate and inhibit regulatory enzymes in cells. We employ X-ray crystallography, using the facilities of the Center, to study these processes at molecular and atomic detail. In collaboration with Sandy Ross's laboratory, we use fluorescence spectroscopy to observe conformational transitions in G proteins at single molecule resolution. 

Field of Study

Structural Biology and Biochemistry: Biological Signal Transduction

Selected Publications

Maziarz M, Leyme A, Marivin A, Luebbers A, Patel PP, Chen Z, Sprang SR, Garcia-Marcos M.Atypical activation of the G protein Gαq by the oncogenic mutation Q209P.J Biol Chem. 2018 Dec 21;293(51):19586-19599. doi: 10.1074/jbc.RA118.005291. Epub 2018 Oct 23.PMID:30352874


Kant R, Zeng B, Thomas, CJ, Bothner, B, Sprang SR (2016) "Ric-8A, a G protein chaperone with nucleotide exchange activity induces long-range secondary structure changes in Gα." eLife. Elife. 2016 Dec 23;5. pii: e19238. doi: 10.7554/eLife.19238 Free PMC Article

Black LA, Thomas CJ, Nix GN, Terwilliger MC, Sprang SR, Ross JBA. "Nanosecond Dynamics of Gαi1 Bound to Nucleotides or Ric-8A, a Gα Chaperone with GEF Activity." Biophys J. 2016 Aug 23;111(4):722-731. doi: 10.1016/j.bpj.2016.07.021.Free PMC Article

Sprang SR Invited review: Activation of G proteins by GTP and the mechanism of Gα-catalyzed GTP hydrolysis. Biopolymers. 2016 Aug;105(8):449-62. doi: 10.1002/bip.22836. Review. PMID: 26996924 Free PMC Article


Van Eps N, Thomas CJ, Hubbell WL, Sprang SR. (2015) "The guanine nucleotide exchange factor Ric-8A induces domain separation and Ras domain plasticity in Galphai1" Proc Natl Acad Sci U S A. 2015 Feb 3;112(5):1404-9. doi: 10.1073/pnas.1423878112. Epub 2015 Jan 20.Free PMC Article

Chan P, Thomas CJ, Sprang SR, Tall GG. (2013) Molecular chaperoning function of Ric-8A is to fold nascent heterotrimeric G protein alpha subunits". Proc Natl Acad Sci U S A. 2013 Mar 5;110(10):3794-9. doi: 10.1073/pnas.1220943110. Epub 2013 Feb 19.PMID:23431197[PubMed - indexed for MEDLINE] Free PMC Article

Thomas CJ, Briknarová K, Hilmer JK, Movahed N, Bothner B, Sumida JP, Tall GG, Sprang SR.(2011) "The nucleotide exchange factor Ric-8A is a chaperone for the conformationally dynamics nucleotide-free state of Galphai1" PLoS One. 2011;6(8):e23197. doi: 10.1371/journal.pone.0023197. Epub 2011 Aug 11.PMID:21853086[PubMed - indexed for MEDLINE]Free PMC Article

Thomas, CJ, Tall, GG, Adhikari, A, Sprang, SR (2008) "Ric-8A catalyzes guanine nucleotide exchange on Galphai1 bound to the GPC/GoLoco exchange inhibitor AGS3" J. Biol. Chem., 283, 23150-60 Free PMC Article

Chen, Z., Singer, WD,  Danesh, SM, Sternweis, PC, Sprang, SR (2008) "Recognition of the activated states of Galpha13 by the rgRGS domain of PDZRhoGEF, Structure, 16, 1532-43 Free PMC Article

Sprang, S.R., Chen, Z and Du, X. (2007)“Structural basis of effector regulation and signal termination in heterotrimeric Ga proteins” Advances Prot. Chem. 74:1-65

Davis, T.,  Bonacci, T.M., Smrcka, AV. and Sprang, S.R. (2005) “Structural and Molecular Characterization  of a Preferred Protein Interaction Surface on G Protein bg Subunits” (2005) Biochemistry 44:10593-10604

Chen, Z., Singer, W.D., Sternweis, P.C. and Sprang, S. R. “Structure of the p115rhoGEF rgRGS domain of-Ga1/i1 chimera complex suggests convergent evolution of a GTPase activator “ (2005), Nature Structural and Molecular Biology, 12:191-7

Mou, T.C., Gille, A., Fancy, DA, Seifert, R and Sprang, S.R.,  (2005) “Structural basis for the inhibition of mammalian adenylyl cyclase by 2’(3’)-O-(N-methylanthraniolyl)-guanosine 5’-triphosphate”  Journal of Biololgical Chemistry, 280:7253-61

 Chen, Z., Singer, W.D., Sternweis, P.C. and Sprang, S. R. “Structure of the p115rhoGEF rgRGS domain of-Ga1/i1 chimera complex suggests convergent evolution of a GTPase activator “ (2005), Nature Structural and Molecular Biology, 12:191-7

Xiao, T, Towb P., Wasserman, S.A. and Sprang, S.R. (1999) Three-Dimensional Structure of a Complex between the Death Domains of Pelle and Tube. Cell 99: 545-555.

Tesmer, J.J.G., Sunahara, R.K., Johnson, R.A., Gosselin G., Gilman, A.G., and Sprang, S.R (1999) Two metal ion catalysis in adenylyl cyclase revealed by its complexes with ATP analogs, Mg2+, Mn2+ and Zn2+. Science 285:756-760.

Tesmer, J. J. G., Sunahara, R. K., Gilman, A. G. and Sprang, S. R. (1997).  Crystal structure of the catalytic domains of adenylyl cyclase in a complex with Gsa•GTPgS. Science 278:1907-1916

Sprang, S. R. (1997).  G Protein Mechanisms: Insights from structural analysis. Annual Review of Biochememistry 66:639-678.

Tesmer, J. J. G., Berman, D. M., Gilman, A. G. and Sprang, S. R. (1997).  Structure of RGS4 bound to AIF4-- activated Gia1: Stabilization of the transition state for GTP hydrolysis.  Cell 89:251-261

Wall, M. A., Coleman, D. E., Lee, E., Iñiguez-Lluhi, J. A., Posner, B. A., Gilman, A. G. and Sprang, S. R. (1995).  The structure of the G protein heterotrimer Giab1g2. Cell 80:1047-105

Sutton, R. B., Davletov, B.A., Berghuis, A. M., Südhof, T. C. and Sprang, S. R. (1995).Structure of the first C2-domain of synaptotagmin I: A novel Ca2+/phospholipid binding fold.  Cell 80:929-938

Naismith, J. H., Devine, T. Q., Brandhuber, B. J. and Sprang, S. R. (1995).  Crystallographic evidence for dimerization of unliganded tumor necrosis factor receptor.  Journal of Biological Chemistry 270:13303-13307.

Coleman, D. E.,  Berghuis, A., Lee, E., Gilman, A. and Sprang, S. (1994). Structures of active conformations of Gia1 and the mechanism of GTP hydrolysis.  Science 265:1405-1412.



Stephen R. Sprang - Google Scholar Citations


Fellow of the American Association for the Advancement of Science, 2000


American Chemical Society

Biophysical Society