ATP-dependent microtubule severing protein that specifically recognizes and cuts microtubules that are polyglutamylated (   ). Preferentially recognizes and acts on microtubules decorated with short polyglutamate tails: severing activity increases as the number of glutamates per tubulin rises from one to eight, but decreases beyond this glutamylation threshold . Severing activity is not dependent on tubulin acetylation or detyrosination . Microtubule severing promotes reorganization of cellular microtubule arrays and the release of microtubules from the centrosome following nucleation. It is critical for the biogenesis and maintenance of complex microtubule arrays in axons, spindles and cilia. SPAST is involved in abscission step of cytokinesis and nuclear envelope reassembly during anaphase in cooperation with the ESCRT-III complex ( ). Recruited at the midbody, probably by IST1, and participates in membrane fission during abscission together with the ESCRT-III complex . Recruited to the nuclear membrane by IST1 and mediates microtubule severing, promoting nuclear envelope sealing and mitotic spindle disassembly during late anaphase . Required for membrane traffic from the endoplasmic reticulum (ER) to the Golgi and endosome recycling . Recruited by IST1 to endosomes and regulates early endosomal tubulation and recycling by mediating microtubule severing . Probably plays a role in axon growth and the formation of axonal branches .
Involved in lipid metabolism by regulating the size and distribution of lipid droplets.
Subcellular locations: Membrane, Endoplasmic reticulum, Midbody, Cytoplasm, Cytoskeleton, Microtubule organizing center, Centrosome, Cytoplasm, Cytoskeleton, Cytoplasm, Perinuclear region, Nucleus, Cytoplasm, Cytoskeleton, Spindle, Cytoplasm, Cell projection, Axon
Forms an intramembrane hairpin-like structure in the membrane . Localization to the centrosome is independent of microtubules . Localizes to the midbody of dividing cells, and this requires CHMP1B . Enriched in the distal axons and branches of postmitotic neurons . Mainly nuclear in interphase cells and becomes associated with the centrosomes, spindle microtubules, midzone and finally the midbody during cell division .
Subcellular locations: Endoplasmic reticulum membrane, Nucleus membrane, Lipid droplet, Cytoplasm, Cytoskeleton, Endosome
Forms an intramembrane hairpin-like structure in the membrane . Recruited to nuclear membrane by IST1 during late anaphase . Localizes to endoplasmic reticulum tubular network .
Subcellular locations: Cytoplasm, Endosome, Nucleus membrane, Cytoplasm, Cytoskeleton, Microtubule organizing center, Centrosome
Constitutes the main endosomal form . Recruited to nuclear membrane by IST1 during late anaphase .
Expressed in brain, heart, kidney, liver, lung, pancreas, placenta and skeletal muscle. The short isoforms may predominate in brain and spinal cord.