2h26
From Proteopedia
human CD1b in complex with endogenous phosphatidylcholine and spacer
Contents |
Overview
CD1 proteins present lipid antigens to T cells. The antigens are acquired in the endosomal compartments. This raises the question of how the large hydrophobic CD1 pockets are preserved between the moment of biosynthesis in the endoplasmic reticulum and arrival to the endosomes. To address this issue, the natural ligands associated with a soluble form of human CD1b have been investigated. Using isoelectric focusing, native mass spectrometry and resolving the crystal structure at 1.8 A resolution, we found that human CD1b is simultaneously associated with endogenous phosphatidylcholine (PC) and a 41-44 carbon atoms-long spacer molecule. The two lipids appear to work in concert to stabilize the CD1b groove, their combined size slightly exceeding the maximal groove capacity. We propose that the spacer serves to prevent binding of ligands with long lipid tails, whereas short-chain lipids might still displace the PC, which is exposed at the groove entrance. The data presented herein explain how the CD1b groove is preserved, and provide a rationale for the in vivo antigen-binding properties of CD1b.
Disease
Known disease associated with this structure: Hypoproteinemia, hypercatabolic OMIM:[109700]
About this Structure
2H26 is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Endogenous phosphatidylcholine and a long spacer ligand stabilize the lipid-binding groove of CD1b., Garcia-Alles LF, Versluis K, Maveyraud L, Vallina AT, Sansano S, Bello NF, Gober HJ, Guillet V, de la Salle H, Puzo G, Mori L, Heck AJ, De Libero G, Mourey L, EMBO J. 2006 Aug 9;25(15):3684-92. Epub 2006 Jul 27. PMID:16874306 Page seeded by OCA on Sun May 4 05:47:03 2008
