ataxin-2: Involved in EGFR trafficking, acting as negative regulator of endocytic EGFR internalization at the plasma membrane. Defects in ATXN2 are the cause of spinocerebellar ataxia type 2 (SCA2); also known as olivopontocerebellar atrophy II (OPCA II or OPCA2). Spinocerebellar ataxia is a clinically and genetically heterogeneous group of cerebellar disorders. Patients show progressive incoordination of gait and often poor coordination of hands, speech and eye movements, due to cerebellum degeneration with variable involvement of the brainstem and spinal cord. SCA2 belongs to the autosomal dominant cerebellar ataxias type I (ADCA I) which are characterized by cerebellar ataxia in combination with additional clinical features like optic atrophy, ophthalmoplegia, bulbar and extrapyramidal signs, peripheral neuropathy and dementia. SCA2 is characterized by hyporeflexia, myoclonus and action tremor and dopamine-responsive parkinsonism. SCA2 is caused by expansion of a CAG repeat resulting in about 36 to 52 repeats in some patients. Longer expansions result in earlier the expansion, onset of the disease. Defects in ATXN2 are a cause of susceptibility to amyotrophic lateral sclerosis type 13 (ALS13). It is a neurodegenerative disorder affecting upper motor neurons in the brain and lower motor neurons in the brain stem and spinal cord, resulting in fatal paralysis. Sensory abnormalities are absent. Death usually occurs within 2 to 5 years. The etiology of amyotrophic lateral sclerosis is likely to be multifactorial, involving both genetic and environmental factors. The disease is inherited in 5-10% of the cases. An increased risk for developing amyotrophic lateral sclerosis is seems to be conferred by CAG repeat intermediate expansions greater than 23 but below the threshold for developing spinocerebellar ataxia. Belongs to the ataxin-2 family. 4 isoforms of the human protein are produced by alternative splicing.
Protein type: Translation; RNA-binding
Chromosomal Location of Human Ortholog: 12q24.1
Cellular Component: nucleoplasm; polysome; Golgi apparatus; membrane; perinuclear region of cytoplasm; stress granule; cytoplasm; trans-Golgi network; ribonucleoprotein complex
Molecular Function: protein C-terminus binding; protein binding; RNA binding; epidermal growth factor receptor binding
Biological Process: regulation of translation; stress granule assembly; negative regulation of multicellular organism growth; RNA metabolic process; neuromuscular process; cerebellar Purkinje cell differentiation; homeostasis of number of cells; cytoplasmic mRNA processing body assembly; neurite morphogenesis; RNA transport; negative regulation of receptor internalization
Disease: Parkinson Disease, Late-onset; Spinocerebellar Ataxia 2
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