alternative products:Alternative promoter usage of a cryptic promoter in exon 1 can direct the synthesis of N-terminally truncated isoforms, which may also arise from alternative initiation,catalytic activity:ATP + H(2)O = ADP + phosphate.,developmental stage:Expressed in fetal brain, heart, kidney, liver, lung, skeletal muscle, spleen and thymus.,disease:Defects in SPAST are the cause of spastic paraplegia autosomal dominant type 4 (SPG4) [MIM:182601]. Spastic paraplegia is a neurodegenerative disorder characterized by a slow, gradual, progressive weakness and spasticity of the lower limbs. Rate of progression and the severity of symptoms are quite variable. Initial symptoms may include difficulty with balance, weakness and stiffness in the legs, muscle spasms, and dragging the toes when walking. In some forms of the disorder, bladder symptoms (such as incontinence) may appear, or the weakness and stiffness may spread to other parts of the body. SPG4 is the most common form of autosomal dominant spastic paraplegias.,function:ATP-dependent microtubule severing protein. Microtubule severing may promote reorganization of cellular microtubule arrays and the release of microtubules from the centrosome following nucleation. Required for membrane traffic from the endoplasmic reticulum (ER) to the Golgi and for completion of the abscission stage of cytokinesis. May also play a role in axon growth and the formation of axonal branches.,online information:The making of crooked -Issue 104 of April 2009,similarity:Belongs to the AAA ATPase family. Spastin subfamily.,similarity:Contains 1 MIT domain.,subcellular location: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. Isoform 3 is the main endosomal form.,subunit:Homohexamer. Binding to ATP stabilizes the homohexameric form. Binds to microtubules at least in part via the alpha-tubulin and beta-tubulin tails. The hexamer may adopt a ring conformation through which microtubules pass prior to being severed. Does not interact strongly with tubulin heterodimers. Interacts (via MIT domain) with CHMP1B; the interaction is direct. Interacts with ATL1, RTN1, SSNA1 and ZFYVE27.,tissue specificity:Expressed in brain, heart, kidney, liver, lung, pancreas, placenta and skeletal muscle. The short isoforms may predominate in brain and spinal cord.,
Membrane ; Peripheral membrane protein . Endoplasmic reticulum . Midbody . Cytoplasm, cytoskeleton, microtubule organizing center, centrosome . Cytoplasm, cytoskeleton . Cytoplasm, perinuclear region . Nucleus . Cytoplasm, cytoskeleton, spindle . Cytoplasm . Forms an intramembrane hairpin-like structure in the membrane (PubMed:20200447). Localization to the centrosome is independent of microtubules (PubMed:15891913). Localizes to the midbody of dividing cells, and this requires CHMP1B (PubMed:18997780). Enriched in the distal axons and branches of postmitotic neurons (PubMed:15269182). .; [Isoform 1]: Endoplasmic reticulum membrane ; Peripheral membrane protein . Nucleus membrane . Lipid droplet . Cytoplasm, cytoskeleton . Endosome . Forms an intramembrane hairpin-like structure in the membrane (PubMed:20200447). Recruited to nuclear membrane by IST1 during late anaphase (PubMed:26040712). Localizes to endoplasmic reticulum tubular network (PubMed:23969831). .; [Isoform 3]: Cytoplasm . Endosome . Nucleus membrane . Constitutes the main endosomal form (PubMed:19000169). Recruited to nuclear membrane by IST1 during late anaphase (PubMed:26040712). .
Expressed in brain, heart, kidney, liver, lung, pancreas, placenta and skeletal muscle. The short isoforms may predominate in brain and spinal cord.