May participate in a complex which severs microtubules in an ATP-dependent manner (By similarity). Microtubule severing may promote rapid reorganization of cellular microtubule arrays (By similarity). Confers precision to microtubule (MT) severing by specific targeting of KTN1 to MT cleavage sites such as crossover or branching nucleation sites (PubMed:28978669). Together with other KTN80s, regulates cell elongation by modulating MT organization (PubMed:28978669). Negative regulator of abscisic acid (ABA) responses (PubMed:21421380). May function as a substrate receptor for cullin-RING ubiquitin ligase 4 complexes (CRL4), a family of E3 ligases involved in protein degradation (PubMed:21421380). Component of KTN80-KTN1 complexes composed of a hexamer of KTN1-KTN80 heterodimers that sense microtubule (MT) geometry to confer precise MT severing (PubMed:28978669). Interacts directly with AAA1/KTN1 (PubMed:28978669). Interacts with subunits of the CUL4-based E3 ligase complex DDB1A and DDB1B (PubMed:21421380). Present in dynamic discrete particles specifically localized to microtubule (MT) crossovers and branching nucleation sites. Expressed at low levels in siliques, flowers, leaves, stems and roots. Hyper-induction of abscisic acid (ABA)-inducible transcription factors (e.g. ABI5 and MYC2) and their downstream genes in response to ABA (PubMed:21421380). Increased sensitivity to ABA and salt stress leading to reduced root length and increased dehydration tolerance (PubMed:21421380). The double mutant ktn80.1 ktn80.2 exhibits normal growth, but the quadruple mutant ktn80.1 ktn80.2 ktn80.3 ktn80.4 has a severe dwarf phenotype, with small and round dark-green rosette leaves as well as wide and short petioles, probably due to cell elongation defects, and associated with a complex cortical microtubule (MT) network with stable entanglements (PubMed:28978669). Plants missing KTN80s have a disruption of KTN1 recruitment at MT crossover or branching nucleation sites, leading to an abolishment of MT severing (PubMed:28978669). Belongs to the WD repeat KATNB1 family.