Spectrin

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Function

Spectrin forms scaffolding in plasma membranes and cytoskeletal structure. It interacts with actin at either end of its tetramer[1]. The SPT dimer is formed by association of α1 and β1 monomers. In invertebrates there are SPT α, β and βH. In vertebrates there are SPT α1 (SPTA1), α2 (SPTA2) and β1 (SPTB1) to β5. SPT contains an SRC Homology 3 domain (SH3), a Pleckstrin Homology (PH) domain and a Calponin Homology (CH) domain.

  • Spectrin α2 is expressed highly in heart muscle cells[2].
  • Spectrin β2 is associated with GABA receptor at dendritic synapses[3].
  • Spectrin β4 is associated with GABA receptor at axon initial segment synapses.
  • Spectrin R16 is spectrin α first repeat domain[4].

Disease

Mutations in SPT α are found in patients with hereditary elliptocytosis[5]. SPT β deficiency is found in hereditary spherocytosis[6].

3D Structures of Spectrin

Spectrin 3D structures

Human spectrin α (grey) and β1 chain (green) 3lbx

Drag the structure with the mouse to rotate

ReferencesReferences

  1. Das A, Base C, Dhulipala S, Dubreuil RR. Spectrin functions upstream of ankyrin in a spectrin cytoskeleton assembly pathway. J Cell Biol. 2006 Oct 23;175(2):325-35. PMID:17060500 doi:http://dx.doi.org/10.1083/jcb.200602095
  2. Bennett PM, Baines AJ, Lecomte MC, Maggs AM, Pinder JC. Not just a plasma membrane protein: in cardiac muscle cells alpha-II spectrin also shows a close association with myofibrils. J Muscle Res Cell Motil. 2004;25(2):119-26. PMID:15360127 doi:10.1023/b:jure.0000035892.77399.51
  3. Smalley JL, Cho N, Ng SFJ, Choi C, Lemons AHS, Chaudry S, Bope CE, Dengler JS, Zhang C, Rasband MN, Davies PA, Moss SJ. Spectrin-beta 2 facilitates the selective accumulation of GABA(A) receptors at somatodendritic synapses. Commun Biol. 2023 Jan 5;6(1):11. PMID:36604600 doi:10.1038/s42003-022-04381-x
  4. Grum VL, Li D, MacDonald RI, Mondragon A. Structures of two repeats of spectrin suggest models of flexibility. Cell. 1999 Aug 20;98(4):523-35. PMID:10481916
  5. Coetzer T, Palek J, Lawler J, Liu SC, Jarolim P, Lahav M, Prchal JT, Wang W, Alter BP, Schewitz G, et al.. Structural and functional heterogeneity of alpha spectrin mutations involving the spectrin heterodimer self-association site: relationships to hematologic expression of homozygous hereditary elliptocytosis and hereditary pyropoikilocytosis. Blood. 1990 Jun 1;75(11):2235-44. PMID:2346784
  6. Dhermy D, Galand C, Bournier O, Cynober T, Mechinaud F, Tchemia G, Garbarz M. Hereditary spherocytosis with spectrin deficiency related to null mutations of the beta-spectrin gene. Blood Cells Mol Dis. 1998 Jun;24(2):251-61. PMID:9714702 doi:http://dx.doi.org/10.1006/bcmd.1998.0190

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Alexander Berchansky, Michal Harel