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Spectroscopy
Volume 26 (2011), Issue 4-5, Pages 213-229
http://dx.doi.org/10.3233/SPE-2011-0543

Structural characterization of recombinant bovine Goα by spectroscopy and homology modeling

Pinar Mega Tiber,1 Oya Orun,1 Cevdet Nacar,1 Ugur Osman Sezerman,2 Feride Severcan,3 Mete Severcan,4 André Matagne,5 and Beki Kan1,6,7

1Department of Biophysics, Marmara University School of Medicine, Istanbul, Turkey
2Biological Sciences and Bioengineering, Sabanci University, Orhanli, Tuzla, Istanbul, Turkey
3Department of Biology, Middle East Technical University, Ankara, Turkey
4Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey
5Laboratory of Enzymology and Protein Folding, Centre for Protein Engineering, Institut de Chimie B6, University of Liége, Liége, Belgium
6Department of Biophysics, School of Medicine, Acibadem University, Istanbul, Turkey
7Department of Biophysics, School of Medicine, Acibadem University, Gulsuyu Mah. Fevzi Cakmak Cad., Divan Sok. No. 1, Maltepe 34848, Istanbul, Turkey

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Go, a member of heterotrimeric guanine nucleotide-binding proteins, is the most abundant form of G protein in the central and peripheral nervous systems. Goα has a significant role in neuronal development and function but its signal transduction mechanism remains to be clarified. In this study, the bovine Goα subunit was overexpressed and purified into homogeneity. Its activity was studied using [35S] GTPγS binding, intrinsic fluorescence and BODIPY assays. The secondary structure was determined by both FTIR and CD spectroscopy as 42.3% α-helix, 13.4% β-sheet and 24.3% β-turn. A theoretical structure model was constructed. The structure from homology modeling is in very good agreement with the crystal structure of mouse Goα subunit except for the loop between αB–αC helices. This model was docked to the mouse RGS16 molecule. T117 on the αB–αC loop of Goα interacted with K172 on RGS16 as opposed to the T117 and K164 interaction in mouse.