SPTAN1 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | SPTAN1 , EIEE5, NEAS, SPTA2, spectrin alpha, non-erythrocytic 1, DEE5 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 182810 MGI: 98386 HomoloGene: 2353 GeneCards: SPTAN1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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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.
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]
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]
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]
SPTAN1 has been shown to interact with:
Protein 4.1,, is a protein associated with the cytoskeleton that in humans is encoded by the EPB41 gene. Protein 4.1 is a major structural element of the erythrocyte membrane skeleton. It plays a key role in regulating membrane physical properties of mechanical stability and deformability by stabilizing spectrin-actin interaction. Protein 4.1 interacts with spectrin and short actin filaments to form the erythrocyte membrane skeleton. Mutations of spectrin and protein 4.1 are associated with elliptocytosis or spherocytosis and anemia of varying severity.
AP-2 complex subunit alpha-1 is a protein that in humans is encoded by the AP2A1 gene.
Alpha-actinin-1 is a protein that in humans is encoded by the ACTN1 gene.
Spectrin alpha chain, erythrocyte is a protein that in humans is encoded by the SPTA1 gene.
Calpain-1 catalytic subunit(CANP 1) is a protein that in humans is encoded by the CAPN1 gene.
Alpha-adducin is a protein that in humans is encoded by the ADD1 gene.
Alpha-actinin-4 is a protein that in humans is encoded by the ACTN4 gene.
Guanine nucleotide-binding protein G(o) subunit alpha is a protein that in humans is encoded by the GNAO1 gene.
Laminin subunit alpha-1 is a protein that in humans is encoded by the LAMA1 gene.
Spectrin beta chain, brain 1 is a protein that in humans is encoded by the SPTBN1 gene.
Beta-adducin is a protein that in humans is encoded by the ADD2 gene.
Tankyrase, also known as tankyrase 1, is an enzyme that in humans is encoded by the TNKS gene. It inhibits the binding of TERF1 to telomeric DNA. Tankyrase attracts substantial interest in cancer research through its interaction with AXIN1 and AXIN2, which are negative regulators of pro-oncogenic β-catenin signaling. Importantly, activity in the β-catenin destruction complex can be increased by tankyrase inhibitors and thus such inhibitors are a potential therapeutic option to reduce the growth of β-catenin-dependent cancers.
Transcription factor NF-E2 45 kDa subunit is a protein that in humans is encoded by the NFE2 gene.
Ena/VASP-like protein is a member of the Ena/VASP family of proteins that in humans is encoded by the EVL gene.
Spectrin beta chain, brain 2 is a protein that in humans is encoded by the SPTBN2 gene.
Rh family, B glycoprotein, also known as RHBG, is an ammonia transporter protein which in humans is encoded by the RHBG gene.
Ankyrin 1, also known as ANK-1, and erythrocyte ankyrin, is a protein that in humans is encoded by the ANK1 gene.
Guanine nucleotide-binding protein subunit alpha-11 is a protein that in humans is encoded by the GNA11 gene. Together with GNAQ, it functions as a Gq alpha subunit.
Ankyrin-2, also known as Ankyrin-B, and Brain ankyrin, is a protein which in humans is encoded by the ANK2 gene. Ankyrin-2 is ubiquitously expressed, but shows high expression in cardiac muscle. Ankyrin-2 plays an essential role in the localization and membrane stabilization of ion transporters and ion channels in cardiomyocytes, as well as in costamere structures. Mutations in ANK2 cause a dominantly-inherited, cardiac arrhythmia syndrome known as long QT syndrome 4 as well as sick sinus syndrome; mutations have also been associated to a lesser degree with hypertrophic cardiomyopathy. Alterations in ankyrin-2 expression levels are observed in human heart failure.
Ankyrin-3 (ANK-3), also known as ankyrin-G, is a protein from ankyrin family that in humans is encoded by the ANK3 gene.