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Crystallographic studies of ligand binding by Zn-α_2-glycoprotein

Delker, Silvia L. and West, Anthony P., Jr. and McDermott, Lindsay and Kennedy, Malcolm W. and Bjorkman, Pamela J. (2004) Crystallographic studies of ligand binding by Zn-α_2-glycoprotein. Journal of Structural Biology, 148 (2). pp. 205-213. ISSN 1047-8477. doi:10.1016/j.jsb.2004.04.009.

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Zn-α_2-glycoprotein (ZAG) is a 41 kDa soluble protein that is present in most bodily fluids. The previously reported 2.8 Å crystal structure of ZAG isolated from human serum demonstrated the structural similarity between ZAG and class I major histocompatibility complex (MHC) molecules and revealed a non-peptidic ligand in the ZAG counterpart of the MHC peptide-binding groove. Here we present crystallographic studies to explore further the nature of the non-peptidic ligand in the ZAG groove. Comparison of the structures of several forms of recombinant ZAG, including a 1.95 Å structure derived from ZAG expressed in insect cells, suggests that the non-peptidic ligand in the current structures and in the structure of serum ZAG is a polyethylene glycol (PEG), which is present in the crystallization conditions used. Further support for PEG binding in the ZAG groove is provided by the finding that PEG displaces a fluorophore-tagged fatty acid from the ZAG binding site. From these results we hypothesize that our purified forms of ZAG do not contain a bound endogenous ligand, but that the ZAG groove is capable of binding hydrophobic molecules, which may relate to its function.

Item Type:Article
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Bjorkman, Pamela J.0000-0002-2277-3990
Additional Information:© 2004 Elsevier Inc. Received 26 March 2004, Available online 19 May 2004. We thank Peter Snow of the Caltech Protein Expression Center for baculovirus expression of ZAG, Luis Sánchez and Elizabeth Sprague for helpful discussions, and members of the Bjorkman laboratory for critical reading of the manuscript. This work was supported by the Cancer Research Fund of the Damon-Runyon Walter Winchell Foundation, Grant DRG-1445 (A.P.W.), a career research award from the Burroughs-Wellcome Fund (A.P.W.), and the Howard Hughes Medical Institute (P.J.B.). L.McD. and M.W.K. are supported by the Wellcome Trust.
Funding AgencyGrant Number
Damon Runyon-Walter Winchell Foundation Cancer Research FundDRG-1445
Burroughs-Wellcome FundUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Subject Keywords:Zn-α2-glycoprotein; MHC homolog; PEG; Ligand
Issue or Number:2
Record Number:CaltechAUTHORS:20170327-143232793
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Official Citation:Silvia L. Delker, Anthony P. West Jr., Lindsay McDermott, Malcolm W. Kennedy, Pamela J. Bjorkman, Crystallographic studies of ligand binding by Zn-α2-glycoprotein, Journal of Structural Biology, Volume 148, Issue 2, November 2004, Pages 205-213, ISSN 1047-8477, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75434
Deposited By: Ruth Sustaita
Deposited On:28 Mar 2017 18:47
Last Modified:15 Nov 2021 16:33

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