THIS ENTRY CONTAINS COORDINATES FOR THE EXTRACELLULAR DOMAINS OF THE MURINE MHC CLASS II ALLELE I- ...THIS ENTRY CONTAINS COORDINATES FOR THE EXTRACELLULAR DOMAINS OF THE MURINE MHC CLASS II ALLELE I-A(G7) WITH A FRAGMENT FROM GAD65 (207 - 220) COVALENTLY ATTACHED TO THE FIRST RESIDUE OF THE AMINO TERMINUS OF THE MATURE BETA CHAIN. THE NUMBERING SCHEME FOR THE I-A(G7) RESIDUES IS AS DESCRIBED IN "SEQUENCES OF PROTEINS OF IMMUNOLOGICAL INTEREST" (1991), EDITED BY E.A. KABAT, T.T. WU, H.M. PERRY, K.S. GOTTESMAN AND C. FOELLER. DIMERIZATION OF THE I-A(G7) HETERODIMER WAS FACILITATED BY ADDING A LEUCINE ZIPPER TAIL TO THE CARBOXY TERMINUS OF EACH CHAIN. IN ADDITION, A HEXAHISTIDINE SEQUENCE WAS ENGINEERED TO THE CARBOXY TERMINAL END OF THE LEUCINE ZIPPER. THIS ALLOWED THE SECRETED PROTEIN TO BE PURIFIED BY NI-NTA CHROMATOGRAPHY. A THROMBIN CUT SITE WAS ENGINEERED IN A SPACER SEQUENCE BETWEEN THE CARBOXY TERMINAL RESIDUE OF EACH CHAIN AND THE LEUCINE ZIPPER- HEXAHISTIDINE SEQUENCE SO THAT MOST OF THE ENGINEERED RESIDUES COULD BE REMOVED FOR CRYSTALLIZATION. AFTER THROMBIN DIGESTION, EIGHT ENGINEERED RESIDUES (SSADLVPR) REMAINED ATTACHED TO THE CARBOXY TERMINAL END OF EACH I-A(G7) CHAIN. NO ELECTRON DENSITY WAS VISIBLE FOR 1) THE FIRST 2 RESIDUES OF THE ALPHA CHAIN 2) THE LAST 6 RESIDUES OF THE SPACER SEQUENCE ATTACHED TO THE C-TERMINUS OF THE ALPHA CHAIN, 3) THE 6 RESIDUE (GSGSGS) LINKER BETWEEN GAD65 AND THE BETA CHAIN, 4) THE FIRST 4 RESIDUES OF THE BETA CHAIN, AND 5) THE LAST 7 RESIDUES OF THE SPACER SEQUENCE ATTACHED TO THE C-TERMINUS OF THE BETA CHAIN. SIX ADDITIONAL RESIDUES (GSHSRG) FROM THE SIGNAL SEQUENCE REMAIN CONNECTED TO THE AMINO TERMINUS OF THE GAD65 PEPTIDE; NO DENSITY IS PRESENT FOR THESE RESIDUES. THE RESIDUE NUMBERING FOR THE TWO PROTEIN CHAINS IS: A 1B - A 178 : MHC CLASS II ALPHA CHAIN A 179 - A 186 : SPACER SEQUENCE B 207P - B 220P : RESIDUES 207-220 OF GAD65 B 1 - B 188 : MHC CLASS II BETA CHAIN B 189 - B 196 : SPACER SEQUENCE
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実験情報
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実験
実験
手法: X線回折 / 使用した結晶の数: 1
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試料調製
結晶
マシュー密度: 2.9 Å3/Da / 溶媒含有率: 57 %
結晶化
温度: 277 K / 手法: 蒸気拡散法, ハンギングドロップ法 / pH: 6.5 詳細: 16-18% PEG 4000, 0.2 M LICL (PH 6.6), 1% MPD, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 277K