Human beta two microglobulin: Difference between revisions
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The first crystal structure of Monomeric human b2m (Mhb2m) is solved in 2002 (pdb 1LDS). The protein is 99 residue in length and has a seven-stranded β sandwich fold typical of the Immunoglobulin superfamily. It is stabilized by a single disulfide bond between | The first crystal structure of Monomeric human b2m (Mhb2m) is solved in 2002 (pdb 1LDS). The protein is 99 residue in length and has a seven-stranded β sandwich fold typical of the Immunoglobulin superfamily. It is stabilized by a single disulfide bond between | ||
Cys-25 and Cys-80, which links the two β sheets. | Cys-25 and Cys-80, which links the two β sheets. | ||
==Structural comparison of MHCb2m and Mhb2m== | ==Structural comparison of MHCb2m and Mhb2m== | ||
Both of the two strucures adopt seven-stranded β sandwich fold with a short C' β strand located in the loop connecting strands C | Both of the two strucures adopt seven-stranded β sandwich fold with a short C' β strand located in the loop connecting strands C | ||
and D. The most significant difference in the ctrystal structures of Mhb2m and MHCb2m involves residues in β strand D and the succeeding loop. When complexed with the MHC heavy chain, residues 50-56 of MHCb2m form two short β strands that separated by a two residue β bulge. These strands (depicted as D1 and D2 in Fig.1) each forms three main-chain-main-chain hydrogen bonds to the adjacent β strand E. The bulge in MHCb2m effectively twists the edge strand, which facilitate its binding to the surface of the heavy chain. However, this β bulge no longer exits in the crytal strucure of Mhb2m. The <scene name='Human_beta_two_microglobulin/D_strand/1'>conformation of D strand </scene>in Mhb2m provides an ideal assembly surface, making this edge-strand pair vulnerable to aggregation. The hydrogen-bonding potential of strand D is satisfied by the formation intermolecular interactionswith adjecent molecules, demonstrating the potential for this region to propagate assembly through edge-strand interactions. | and D. The most significant difference in the ctrystal structures of Mhb2m and MHCb2m involves residues in β strand D and the succeeding loop. When complexed with the MHC heavy chain, residues 50-56 of MHCb2m form two short β strands that separated by a two residue β bulge. These strands (depicted as D1 and D2 in Fig.1) each forms three main-chain-main-chain hydrogen bonds to the adjacent β strand E. The bulge in MHCb2m effectively twists the edge strand, which facilitate its binding to the surface of the heavy chain. However, this β bulge no longer exits in the crytal strucure of Mhb2m. The <scene name='Human_beta_two_microglobulin/D_strand/1'>conformation of D strand </scene>in Mhb2m provides an ideal assembly surface, making this edge-strand pair vulnerable to aggregation. The hydrogen-bonding potential of strand D is satisfied by the formation intermolecular interactionswith adjecent molecules, demonstrating the potential for this region to propagate assembly through edge-strand interactions. | ||
