1ja3
From Proteopedia
|
Crystal Structure of the Murine NK Cell Inhibitory Receptor Ly-49I
Overview
Natural killer (NK) cells play a crucial role in the detection and, destruction of virally infected and tumor cells during innate immune, responses. The cytolytic activity of NK cells is regulated through a, balance of inhibitory and stimulatory signals delivered by NK receptors, that recognize classical major histocompatabilty complex class I (MHC-I), molecules, or MHC-I homologs such as MICA, on target cells. The Ly49, family of NK receptors (Ly49A through W), which includes both inhibitory, and activating receptors, are homodimeric type II transmembrane, glycoproteins, with each subunit composed of a C-type lectin-like domain, tethered to the membrane by a stalk region. We have determined the crystal, structure, at 3.0 A resolution, of the murine inhibitory NK receptor, Ly49I. The Ly49I monomer adopts a fold similar to that of other C-type, lectin-like NK receptors, including Ly49A, NKG2D and CD69. However, the, Ly49I monomers associate in a manner distinct from that of these other NK, receptors, forming a more open dimer. As a result, the putative, MHC-binding surfaces of the Ly49I dimer are spatially more distant than, the corresponding surfaces of Ly49A or NKG2D. These structural differences, probably reflect the fundamentally different ways in which Ly49 and NKG2D, receptors recognize their respective ligands: whereas the single MICA, binding site of NKG2D is formed by the precise juxtaposition of two, monomers, each Ly49 monomer contains an independent binding site for, MHC-I. Hence, the structural constraints on dimerization geometry may be, relatively relaxed within the Ly49 family. Such variability may enable, certain Ly49 receptors, like Ly49I, to bind MHC-I molecules bivalently, thereby stabilizing receptor-ligand interactions and enhancing signal, transmission to the NK cell.
About this Structure
1JA3 is a Single protein structure of sequence from Mus musculus. Full crystallographic information is available from OCA.
Reference
Crystal structure of the Ly49I natural killer cell receptor reveals variability in dimerization mode within the Ly49 family., Dimasi N, Sawicki MW, Reineck LA, Li Y, Natarajan K, Margulies DH, Mariuzza RA, J Mol Biol. 2002 Jul 12;320(3):573-85. PMID:12096910
Page seeded by OCA on Sat Nov 24 23:20:28 2007
