1T7Z

Zn-alpha-2-glycoprotein; baculo-ZAG no PEG, no glycerol

Summary for 1T7Z

• Entry DOI: 10.2210/pdb1t7z/pdb
• Related: 1ZAG 1t7v 1t7w 1t7x 1t7y 1t80
• Descriptor: Zinc-alpha-2-glycoprotein, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: mhc class i homolog, lipid binding protein
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 32831.56

Authors

Delker, S.L.,West Jr., A.P.,McDermott, L.,Kennedy, M.W.,Bjorkman, P.J. (deposition date: 2004-05-11, release date: 2004-12-21, Last modification date: 2024-10-30)

Primary citation

Delker, S.L.,West Jr., A.P.,McDermott, L.,Kennedy, M.W.,Bjorkman, P.J.
Crystallographic studies of ligand binding by Zn-alpha2-glycoprotein.
J.Struct.Biol., 148:205-213, 2004

PubMed Abstract: Zn-alpha2-glycoprotein (ZAG) is a 41 kDa soluble protein that is present in most bodily fluids. The previously reported 2.8 A 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 A 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.

PubMed: 15477100
DOI: 10.1016/j.jsb.2004.04.009

Experimental method

X-RAY DIFFRACTION (3 Å)