The C‐Terminal Domain of α‐Spectrin is Structurally Related to Calmodulin

Travé, Gilles; Pastore, Annalisa; Hyvönen, Marko; Saraste, Matti

doi:10.1111/j.1432-1033.1995.tb20357.x

Cited by 46 publications

(50 citation statements)

References 58 publications

(46 reference statements)

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“…The 2 most N-terminal EF hands 1 and 2 are homologous to those in calmodulin. 13 They bind calcium with low affinity, and calcium binding induces a conformational change in the domain. 14 The more C-terminal EF hands 3 and 4 are calcium independent and structurally similar to those in ␣-actinin.…”

Section: Introductionmentioning

confidence: 99%

Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in α-spectrin–deficient red cells

Robledo

Lambert

Birkenmeier

et al. 2010

Blood

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Five spontaneous, allelic mutations in the ␣-spectrin gene, Spna1, have been identified in mice (spherocytosis [sph], sph 1J , sph 2J , sph 2BC , sph Dem ). All cause severe hemolytic anemia. Here, analysis of 3 new alleles reveals previously unknown consequences of red blood cell (RBC) spectrin deficiency. In sph 3J , a missense mutation (H2012Y) in repeat 19 introduces a cryptic splice site resulting in premature termination of translation. In sph Ihj , a premature stop codon occurs (Q1853Stop) in repeat 18. Both mutations result in markedly reduced RBC membrane spectrin content, decreased band 3, and absent ␤-adducin. Reevaluation of available, previously described sph alleles reveals band 3 and adducin deficiency as well. In sph 4J , a missense mutation occurs in the C-terminal EF hand domain (C2384Y). Notably, an equally severe hemolytic anemia occurs despite minimally decreased membrane spectrin with normal band 3 levels and present, although reduced, ␤-adducin. The severity of anemia in sph 4J indicates that the highly conserved cysteine residue at the C-terminus of ␣-spectrin participates in interactions critical to membrane stability. The data reinforce the notion that a membrane bridge in addition to the classic protein 4.1-p55-glycophorin C linkage exists at the RBC junctional complex that involves interactions between spectrin, adducin, and band 3. (Blood. 2010;115:1804-1814) IntroductionThe membrane skeleton, a multiprotein complex attached to the cytoplasmic surface of the red blood cell (RBC) lipid bilayer, is critical to RBC strength and deformability. 1 The major component of the skeleton, spectrin, consists of ␣ and ␤ subunits, encoded in mice by the Spna1 and Spnb1 genes, respectively. 2 Spectrin tetramers are cross-linked into a 2-dimensional hexagonal array by short actin protofilaments at "junctional complexes," which also include protein 4.1, dematin (protein 4.9), adducin, tropomyosin, tropomodulin, and p55. 3 The spectrin array is attached to the overlying plasma membrane by ankyrin, which binds ␤-spectrin to the integral membrane protein band 3 (anion exchanger, SLC4A1), and by protein 4.1-p55-glycophorin C interactions at the junctional complexes. The structural components and function of the RBC membrane skeleton have been comprehensively reviewed elsewhere. 2,[4][5][6][7] Each spectrin molecule is composed of a series of approximately 106 amino acid repeats that fold into triple helices; ␣-spectrin contains 21 numbered repeats, although repeat 10 is actually an SH3 domain, and ␤-spectrin contains 16 repeats. 6 ␣-and ␤-spectrin align side-to-side ("nucleate") in an antiparallel manner to form heterodimers. 8 Repeats 18 to 21 at the C-terminus of ␣-spectrin and repeats 1 to 4 at the N-terminus of ␤-spectrin form the nucleation site that initiates "zippering" of the 2 subunits together via electrostatic interactions. 6,9,10 Heterodimers selfassociate to form heterotetramers, the major form of spectrin in RBCs. The self-association site is at opposite ends of the respective nucleation si...

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Section: Introductionmentioning

confidence: 99%

Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in α-spectrin–deficient red cells

Robledo

Lambert

Birkenmeier

et al. 2010

Blood

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“…As noted, the EF-domain is structurally similar to calmodulin (3,9) and has four EF-hands. The amino-terminal EF-hands are functional and bind Ca 2ϩ with dissociation constants in the low millimolar range (K d ϳ 0.5 mM) (3).…”

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confidence: 84%

“…The heterodimers interact with each other at their head ends through incomplete spectrin repeats (␣0 and ␤17) to form heterotetramers. The tail ends of the heterodimers are capped with specialized domains; that is, an actin binding domain (ABD) 3 in the case of ␤-spectrin and the EF-domain in ␣-spectrin. The ABD contains two calponin homology domains.…”

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confidence: 99%

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confidence: 99%

“…The amino-terminal EF-hands are functional and bind Ca 2ϩ with dissociation constants in the low millimolar range (K d ϳ 0.5 mM) (3). The carboxyl-terminal (distal) pair does not bind Ca 2ϩ (3). Like calmodulin, Ca 2ϩ binding causes the proximal EF-hands in brain spectrin to change from a "closed" to an "open" state (9).…”

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Protein 4.2 Binds to the Carboxyl-terminal EF-hands of Erythroid α-Spectrin in a Calcium- and Calmodulin-dependent Manner

Korsgren

Peters

Lux

2010

Journal of Biological Chemistry

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Spectrin and protein 4.1 cross-link F-actin protofilaments into a network called the membrane skeleton. Actin and 4.1 bind to one end of ␤-spectrin. The adjacent end of ␣-spectrin, called the EF-domain, is calmodulin-like, with calcium-dependent and calcium-independent EF-hands. It has no known function. However, the sph 1J /sph 1J mouse has very fragile red cells and lacks the last 13 amino acids in the EF-domain, suggesting the domain is critical for skeletal integrity. Using pulldown binding assays, we find the ␣-spectrin EF-domain either alone or incorporated into a mini-spectrin binds native and recombinant protein 4.2 at a previously identified region of 4.2 (G 3 peptide 2؉ -independent binding. The data suggest that protein 4.2 is located near protein 4.1 at the spectrin-actin junctions. Because proteins 4.1 and 4.2 also bind to band 3, the erythrocyte anion channel, we suggest that one or both of these proteins cause a portion of band 3 to localize near the spectrinactin junctions and provide another point of attachment between the membrane skeleton and the lipid bilayer.The red blood cell membrane skeleton is composed principally of short F-actin filaments cross-linked by ␣ 2 ␤ 2 -spectrin heterotetramers with the assistance of protein 4.1 2 to form a roughly hexagonal array (1). Actin and protein 4.1 bind to the actin binding domain at the amino terminus of the spectrin ␤-chain (2). The adjacent, carboxyl-terminal end of ␣-spectrin contains a calmodulin-like domain (3) (amino acids 2262-2418 in human ␣-spectrin) that is called the EF-domain and is thought to be inert and vestigial. However, the sph 1J /sph 1J mouse (4), which has severe hereditary spherocytosis and unstable red cell membranes, makes a mutant ␣-spectrin that lacks the last 13 amino acids of the EF-domain. The mutant protein is overexpressed by severalfold but is poorly incorporated into the red blood cell membrane skeleton (4), showing that the domain has some important but undiscovered function.The complex formed by spectrin, actin, and protein 4.1 is part of a larger structure called the "junctional complex," which also contains adducin, dematin, tropomyosin, tropomodulin, and p55 (5) and, according to recent work, is attached to integral membrane protein complexes containing various combinations of band 3, glucose transporter-1, the Kell and Duffy glycoproteins, the Rh protein, the XK protein, and glycophorin C (6 -8).The ␣-and ␤-spectrin chains are mostly composed of ϳ106 amino acid, triple-helical subunits joined in tandem. There are 21 numbered repeats in ␣-spectrin (though "repeat" 10 is actually an SH3 domain inserted in repeat 9) and 16 repeats in ␤-spectrin. The two chains are aligned side-by-side in an antiparallel arrangement and variably coiled about each other. The heterodimers interact with each other at their head ends through incomplete spectrin repeats (␣0 and ␤17) to form heterotetramers. The tail ends of the heterodimers are capped with specialized domains; that is, an actin binding domain (ABD) 3 in the case of ␤-...

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2009

Metalloproteomics

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The C‐Terminal Domain of α‐Spectrin is Structurally Related to Calmodulin

Cited by 46 publications

References 58 publications

Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in α-spectrin–deficient red cells

Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in α-spectrin–deficient red cells

Protein 4.2 Binds to the Carboxyl-terminal EF-hands of Erythroid α-Spectrin in a Calcium- and Calmodulin-dependent Manner

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