9wz5

Full-length ASC-CARD filament

spinqualitylabelsall models 9wz5, resolution 2.91Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9wz5 is a 12 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.91Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function ASC_HUMAN Functions as key mediator in apoptosis and inflammation. Promotes caspase-mediated apoptosis involving predominantly caspase-8 and also caspase-9 in a probable cell type-specific manner. Involved in activation of the mitochondrial apoptotic pathway, promotes caspase-8-dependent proteolytic maturation of BID independently of FADD in certain cell types and also mediates mitochondrial translocation of BAX and activates BAX-dependent apoptosis coupled to activation of caspase-9, -2 and -3. Involved in macrophage pyroptosis, a caspase-1-dependent inflammatory form of cell death and is the major constituent of the ASC pyroptosome which forms upon potassium depletion and rapidly recruits and activates caspase-1. In innate immune response believed to act as an integral adapter in the assembly of the inflammasome which activates caspase-1 leading to processing and secretion of proinflammatory cytokines. The function as activating adapter in different types of inflammasomes is mediated by the DAPIN and CARD domains and their homotypic interactions. Required for recruitment of caspase-1 to inflammasomes containing certain pattern recognition receptors, such as NLRP2, NLRP3, AIM2 and probably IFI16. In the NLRP1 and NLRC4 inflammasomes seems not be required but facilitates the processing of procaspase-1. In cooperation with NOD2 involved in an inflammasome activated by bacterial muramyl dipeptide leading to caspase-1 activation. May be involved in DDX58-triggered proinflammatory responses and inflammasome activation. Isoform 2 may have a regulating effect on the function as inflammasome adapter. Isoform 3 seems to inhibit inflammasome-mediated maturation of interleukin-1 beta. In collaboration with AIM2 which detects cytosolic double-stranded DNA may also be involved in a caspase-1-independent cell death that involves caspase-8. In adaptive immunity may be involved in maturation of dendritic cells to stimulate T-cell immunity and in cytoskeletal rearrangements coupled to chemotaxis and antigen uptake may be involved in post-transcriptional regulation of the guanine nucleotide exchange factor DOCK2; the latter function is proposed to involve the nuclear form. Also involved in transcriptional activation of cytokines and chemokines independent of the inflammasome; this function may involve AP-1, NF-kappa-B, MAPK and caspase-8 signaling pathways. For regulation of NF-kappa-B activating and inhibiting functions have been reported. Modulates NF-kappa-B induction at the level of the IKK complex by inhibiting kinase activity of CHUK and IKBK. Proposed to compete with RIPK2 for association with CASP1 thereby down-regulating CASP1-mediated RIPK2-dependent NF-kappa-B activation and activating interleukin-1 beta processing. Publication Abstract from PubMed ASC (Apoptosis-associated Speck-like protein containing a CARD) is a key adaptor protein that assembles inflammasomes by linking sensors such as NLRP3 to effectors like Caspase-1 via its PYD and CARD Death Domains. Due to ASC's propensity to self-aggregate, most high-resolution structural studies focused on isolated PYD or CARD domains, leaving the atomic basis of full-length ASC assembly unknown. Here we determine atomic-resolution cryo-EM structures of PYD and CARD filaments from full-length ASC, revealing characteristic multitrack bundles composed of alternating ASC(PYD) and ASC(CARD) filaments that expose multiple interfaces for flexible assembly and efficient signaling. We further show that Caspase-1 filaments nucleate specifically from the B-end of ASC(CARD) filaments, and that the interdomain linker modulates bundle formation. The ASC isoform ASCb, with a four-residue linker, adopts a distinct architecture, correlating with reduced Caspase-1 activation efficiency. In ASC((-)/(-)) THP-1 cells, only wild-type ASC, not interface-disrupting mutants, restored ASC speck formation and Caspase-1 activation, underscoring the requirement for intact multitrack bundles. Cryo-electron tomography captures snapshots of higher-order inflammasome structures. These findings collectively define the structural and functional principles by which ASC organizes inflammasomes to amplify immune signaling. Atomic mechanisms of full-length ASC-mediated inflammasome assembly.,Xue D, Ni F, Liu S, Yan H, Luo Z, Fu G, Wang Q, Ma J Nat Commun. 2025 Nov 26;16(1):10564. doi: 10.1038/s41467-025-65578-2. PMID:41298390 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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