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SPTAN1
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	2FOT, 3F31, 3FB2
Identifiers
Aliases	SPTAN1, EIEE5, NEAS, SPTA2, spectrin alpha, non-erythrocytic 1, DEE5
External IDs	OMIM: 182810; MGI: 98386; HomoloGene: 2353; GeneCards: SPTAN1; OMA:SPTAN1 - orthologs
Gene location (Human)
Chr.	Chromosome 9 (human)
End	128,633,662 bp
Gene location (Mouse)
Chr.	Chromosome 2 (mouse)
End	29,921,463 bp
RNA expression pattern
	Top expressed in
	right hemisphere of cerebellum; ; right frontal lobe; ; Brodmann area 9; ; Amygdala; ; right uterine tube; ; nucleus accumbens; ; prefrontal cortex; ; Brodmann area 10; ; cingulate gyrus; ; tibial nerve;
	Top expressed in
	facial motor nucleus; ; epithelium of lens; ; dentate gyrus of hippocampal formation granule cell; ; ciliary body; ; Rostral migratory stream; ; cerebellar cortex; ; iris; ; anterior horn of spinal cord; ; barrel cortex; ; external carotid artery;
	More reference expression data
	; ;
	More reference expression data
Gene ontology
Molecular function	calcium ion binding; metal ion binding; calmodulin binding; structural constituent of cytoskeleton; protein binding; actin binding; cadherin binding;
Cellular component	cytoplasm; extracellular vesicle; cytosol; spectrin; membrane; intracellular membrane-bounded organelle; microtubule cytoskeleton; cell cortex; extracellular exosome; cytoskeleton; extracellular region; specific granule lumen; tertiary granule lumen;
Biological process	MAPK cascade; axon guidance; endoplasmic reticulum to Golgi vesicle-mediated transport; actin filament capping; cytoskeleton organization; neutrophil degranulation; regulation of molecular function;
	Sources:Amigo / QuickGO
Orthologs
	6709
	20740
	ENSG00000197694
	ENSMUSG00000057738
	Q13813
	P16546
NM_001130438; NM_001195532; NM_003127; NM_001363759; NM_001363765;
	NM_001375310; NM_001375311; NM_001375312; NM_001375313; NM_001375314; NM_001375318
	NM_001076554; NM_001177667; NM_001177668; NM_001309460; NM_001369325
NP_001123910; NP_001182461; NP_003118; NP_001350688; NP_001350694;
	NP_001362239; NP_001362240; NP_001362241; NP_001362242; NP_001362243; NP_001362247
	NP_001171138; NP_001171139; NP_001296389; NP_001356254
	Wikidata
View/Edit Human	View/Edit Mouse

Alpha II-spectrin, also known as Spectrin alpha chain, brain is a protein that in humans is encoded by the SPTAN1 gene.^[5]^[6]^[7] Alpha II-spectrin is expressed in a variety of tissues, and is highly expressed in cardiac muscle at Z-disc structures, costameres and at the sarcolemma membrane. Mutations in alpha II-spectrin have been associated with early infantile epileptic encephalopathy-5, and alpha II-spectrin may be a valuable biomarker for Guillain–Barré syndrome and infantile congenital heart disease.

Structure

Alternate splicing of alpha II-spectrin has been documented and results in multiple transcript variants; specifically, cardiomyocytes have four identified alpha II-spectrin splice variants.^[8]^[9] As opposed to alpha I-spectrin that is principally found in erythrocytes,^[10] alpha II-spectrin is expressed in most tissues. In cardiac tissue, alpha II-spectrin is found in myocytes at Z-discs, costameres, and the sarcolemma membrane,^[11]^[12]^[13] and in cardiac fibroblasts along the surface of the cytoskeletal network.^[14] Alpha II-spectrin most commonly exists in a heterodimer with alpha II and beta II spectrin subunits; and dimers typically self-associate and heterotetramerize.^[5]^[15]^[16]

Function

The spectrins are a family of widely distributed cytoskeletal proteins which are involved in actin crosslinking, cell adhesion, intercellular communication and cell cycle regulation.^[17]^[18]^[19] Though a role in cardiac muscle is not well understood, it is likely that alpha II-spectrin is involved in organizing sub-sarcolemmal domains and stabilizing sarcolemmal membranes against the stresses associated with continuous cardiac contraction.^[16] Functional diversity of alpha II-spectrin is manifest through its four splice variants. First, a cardiac-specific, 21 amino acid sequence insert in the 21st spectrin repeat, termed alpha II-cardi+, was identified as an insert that modulates affinity of alpha II-spectrin for binding beta-spectrins and regulates myocyte growth and differentiation.^[8] Secondly, another insert of 20 amino acids in the 10th spectrin repeat, termed SH3i+, contains protein kinase A and protein kinase C phosphorylation sites and modulates Ca2+-dependent cleavage of spectrin and protein-protein interaction properties.^[20] Thirdly, an insert of five amino acids in the fifteenth spectrin motif bears a highly antigenic epitope resembling an ankyrin-like p53 binding protein binding site.^[8]^[21] Fourthly, a six amino acid insert in the twenty-first spectrin motif with unknown function has been reported.^[11]^[22]

Alpha II-spectrin gene expression has been shown to be upregulated in cardiac fibroblasts in response to Angiotensin II-induced cardiac remodeling.^[23]

In animal models of disease and injury, alpha II-spectrin has been implicated in diverse functions. In a canine model of hypothermic circulatory arrest, alpha II-spectrin breakdown products have shown to be relevant markers of neurologic injury post-cardiac surgery.^[24]

Clinical significance

Mutations in SPTAN1 are the cause of early infantile epileptic encephalopathy-5.^[25]

Alpha II-spectrin has shown promising utility as a biomarker for brain necrosis and apoptosis in infants with congenital heart disease; breakdown products of alpha II-spectrin have been detected in the serum of neonates in the perioperative period and following open-heart surgery.^[26] Elevated protein expression of alpha II-spectrin has been detected in cerebrospinal fluid in patients with Guillain–Barré syndrome.^[27]