Isothermal titration calorimetric study defines the substrate binding residues of calreticulin

Gopalakrishnapai, Jayashree and Gupta, Garima and Karthikeyan, T and Sinha, Sharmistha and Kandiah, Eaazhisai and Gemma, Emiliano and Oscarson, Stefan and Surolia, Avadhesha (2006) Isothermal titration calorimetric study defines the substrate binding residues of calreticulin. In: Biochemical and Biophysical Research Communications, 351 (1). pp. 14-20.

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Abstract

Earlier we established using modeling studies the residues in calreticulin (CRT) important for sugar-binding (M. Kapoor, H. Srinivas, K. Eaazhisai, E. Gemma, L. Ellgaard, S. Oscarson, A. Helenius, A. Surolia, Interactions of substrate with calreticulin, an endoplasmic reticulum chaperone, J. Biol. Chem. 278 (8) (2003) 6194–6200). Here, we discuss the relative roles of Trp-319, Asp-317, and Asp-160 for sugar-binding by using site-directed mutagenesis and isothermal titration calorimetry (ITC). Residues corresponding to Asp-160 and Asp-317 in CNX play important role towards sugar-binding. From the present study we demonstrate that the residue Asp-160 is not involved in sugar-binding, while Asp-317 plays a crucial role. Further, it is also validated that cation–\pi interactions of the sugar with Trp-319 dictate sugar-binding in CRT. This study not only defines further the binding site of CRT but also highlights its subtle differences with that of calnexin.

Item Type:	Journal Article
Publication:	Biochemical and Biophysical Research Communications
Additional Information:	Copyright of this article belongs to Elsevier.
Keywords:	Calreticulin;Calnexin;Isothermal titration calorimetry;Carbohydrate-binding site
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	13 Dec 2006
Last Modified:	19 Sep 2010 04:33
URI:	http://eprints.iisc.ac.in/id/eprint/9089

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