2AG4

Crystal Structure Analysis of GM2-activator protein complexed with phosphatidylcholine

2AG4 の概要

• エントリーDOI: 10.2210/pdb2ag4/pdb
• 関連するPDBエントリー: 1G13 1PU5 1PUB 1TJJ
• 分子名称: Ganglioside GM2 activator, (7R)-4,7-DIHYDROXY-N,N,N-TRIMETHYL-10-OXO-3,5,9-TRIOXA-4-PHOSPHAHEPTACOSAN-1-AMINIUM 4-OXIDE, OLEIC ACID, ... (5 entities in total)
• 機能のキーワード: complex of single chain lipid and fatty acids, lipid binding protein
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Lysosome: P17900
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 37990.56

構造登録者

Wright, C.S.,Mi, L.Z.,Lee, S.,Rastinejad, F. (登録日: 2005-07-26, 公開日: 2005-10-25, 最終更新日: 2024-10-30)

主引用文献

Wright, C.S.,Mi, L.Z.,Lee, S.,Rastinejad, F.
Crystal Structure Analysis of Phosphatidylcholine-GM2-Activator Product Complexes: Evidence for Hydrolase Activity.
Biochemistry, 44:13510-13521, 2005

PubMed Abstract: GM2-activator protein (GM2AP) is a lysosomal lipid transfer protein with important biological roles in ganglioside catabolism, phospholipid metabolism, and T-cell activation. Previous studies of crystal structures of GM2AP complexed with the physiological ligand GM2 and platelet activating factor (PAF) have shown binding at two specific locations within the spacious apolar pocket and an ordering effect of endogenous resident lipids. To investigate the structural basis of phospholipid binding further, GM2AP was cocrystallized with phosphatidylcholine (PC), known to interact with GM2AP. Analysis of three crystal forms revealed binding of single chain lipids and fatty acids only and surprisingly not intact PC. The regions of best defined electron density are consistent with the presence of lyso-PC and oleic acid, which constitute deacylation products of PC. Their acyl tails are in stacking contact with shorter, less well-defined stretches of electron density that may represent resident fatty acids. The GM2AP associated hydrolytic activity that generates lyso-PC was further confirmed by mass spectrometry and enzymatic assays. In addition, we report the structures of (i) mutant Y137S, assessing the role of Tyr137 in lipid transfer via the hydrophobic cleft, and (ii) apo-mouse GM2AP, revealing a hydrophobic pocket with a constricted opening. Our structural results provide new insights into the biological functions of GM2AP. The combined effect of hydrolytic and lipid transfer properties has profound implications in cellular signaling.

PubMed: 16216074
DOI: 10.1021/bi050668w

実験手法

X-RAY DIFFRACTION (1.8 Å)