{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Potassium channel tetramerization domain containing 5 (KCTD5) is emerging as a multifunctional adaptor that confers substrate specificity to Cullin3‐based ubiquitin ligase complexes and thereby regulates diverse signaling outputs and protein turnover events. Structural studies have revealed that KCTD5 adopts a stable, pentameric architecture with a conserved BTB (POZ) domain that mediates high‐affinity interactions with Cul3 as well as other substrates; these features distinguish it from other members of the KCTD family (see, for example."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": " Functionally, KCTD5 has been implicated in downregulating pro‐survival signaling cascades by acting as a negative regulator of the AKT pathway. In this context, it functions as an “off‐switch” for G protein–coupled receptor signaling by facilitating the ubiquitin‐dependent proteolysis of dissociated Gβγ subunits."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition, KCTD5 participates in modulating transcriptional activity; for instance, its interaction with ΔNp63α leads to monoubiquitination of this transcription factor, which in turn diminishes ΔNp63α’s DNA‐binding affinity and curbs its pro‐proliferative action."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " KCTD5 has also been shown to interact with viral Rep proteins, with wild‐type Rep triggering a redistribution of KCTD5 into the nucleus and thereby altering viral gene activation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Biochemical and structural characterizations have further detailed that KCTD5 forms a well‐defined 5:5 heterodecamer with Cul3"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": ", while innovative approaches using stapled Cul3‐derived peptides have confirmed that its BTB domain can be effectively targeted and modulated."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "10"}]}, {"type": "t", "text": " Collectively, these studies position KCTD5 as a key regulator of ubiquitination processes—with significant roles in attenuating GPCR‐mediated AKT activation and modulating transcription factor activity—that impact cellular homeostasis and may contribute to disease pathogenesis.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Irina S Dementieva, Valentina Tereshko, Zoe A McCrossan, et al. 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