Sandbox Reserved 1785

This Sandbox is Reserved from February 27 through August 31, 2023 for use in the course CH462 Biochemistry II taught by R. Jeremy Johnson at the Butler University, Indianapolis, USA. This reservation includes Sandbox Reserved 1765 through Sandbox Reserved 1795.

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Human B-cell Antigen Receptor: IgM BCR

spinqualitylabelsall models IgM B-Cell Receptor (PDB: 7xq8) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structure colored by domain colored by chain Transmembrane Region The IgM BCR is tethered to B-cell membranes through the transmembrane region which is broken up into both extracellular and integral domains. IgM BCR assembly requires dimerization of the Ig alpha and Ig beta subunits which embed within the B-cell membrane. The Ig alpha and beta heterodimer is dimerized in both the integral region, with a hydrogen bond, and within the extracellular region with a disulfide bridge. Although the mechanism of disulfide bridge formation is still unknown, it is believed that extracellular glycosylation via N-linked glycosylation (NAGs, shown in green) of various asparagine residues in the extracellular region of both the alpha and Ig beta chains help to facilitate this process. Chaperon proteins remain bound to the alpha and beta subunits until both dimerizations occur at which point the rest of the BCR complex can be recruited. After Ig alpha/Ig beta dimerization the transmembrane helices of the heavy chains can embed within the B-cell membrane as well. The side chains of this 4-pass integral helix structure are primarily hydrophobic side chains that allow for interactions with the hydrophobic tails in the phospholipid bilayer. A total of 9 polar residues (picture that zooms in here??) between each of the heavy chains are included on the interior of the helix structure which interact with a few polar residues on the Ig alpha and Ig beta chains to hold the complex together. Additional interactions between the Ig alpha/Ig beta dimer and the heavy chains occur in the constant region. Fab Region Heavy-Light Chain Interface Variable Region Figure Legend