7s64

Intermediate-form oocyte/egg Alpha-2-Macroglobulin (A2Moo) tetramer

spinqualitylabelsall models 7s64, resolution 6.43Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7s64 is a 4 chain structure with sequence from Xenopus laevis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Alpha-2-Macroglobulin (A2M) is the critical pan-protease inhibitor of the innate immune system. When proteases cleave the A2M bait region, global structural transformation of the A2M tetramer is triggered to entrap the protease. The structural basis behind the cleavage-induced transformation and the protease entrapment remains unclear. Here, we report cryo-EM structures of native- and intermediate-forms of the Xenopus laevis egg A2M homolog (A2Moo or ovomacroglobulin) tetramer at 3.7-4.1 A and 6.4 A resolution, respectively. In the native A2Moo tetramer, two pairs of dimers arrange into a cross-like configuration with four 60 A-wide bait-exposing grooves. Each bait in the native form threads into an aperture formed by three macroglobulin domains (MG2, MG3, MG6). The bait is released from the narrowed aperture in the induced protomer of the intermediate form. We propose that the intact bait region works as a "latch-lock" to block futile A2M transformation until its protease-mediated cleavage. Structural Mechanics of the Alpha-2-Macroglobulin Transformation.,Arimura Y, Funabiki H J Mol Biol. 2021 Dec 20:167413. doi: 10.1016/j.jmb.2021.167413. PMID:34942166 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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