Crystal structure of the complex between calmodulin and alphaII-spectrin
[SPTA2_HUMAN] Defects in SPTAN1 are the cause of epileptic encephalopathy early infantile type 5 (EIEE5) [MIM:613477]. EIEE5 is a disorder characterized by seizures associated with hypsarrhythmia profound mental retardation with lack of visual attention and speech development, as well as spastic quadriplegia.
[CALM_BOVIN] Calmodulin mediates the control of a large number of enzymes, ion channels and other proteins by Ca(2+). Among the enzymes to be stimulated by the calmodulin-Ca(2+) complex are a number of protein kinases and phosphatases. Together with CEP110 and centrin, is involved in a genetic pathway that regulates the centrosome cycle and progression through cytokinesis (By similarity). [SPTA2_HUMAN] Fodrin, which seems to be involved in secretion, interacts with calmodulin in a calcium-dependent manner and is thus candidate for the calcium-dependent movement of the cytoskeleton at the membrane.
Publication Abstract from PubMed
AlphaII-spectrin is a major cortical cytoskeletal protein contributing to membrane organization and integrity. The Ca2+-activated binding of calmodulin to an unstructured insert in the 11th repeat unit of alphaII-spectrin enhances the susceptibility of spectrin to calpain cleavage but abolishes its sensitivity to several caspases and to at least one bacterially derived pathologic protease. Other regulatory inputs including phosphorylation by c-Src also modulate the proteolytic susceptibility of alphaII-spectrin. These pathways, acting through spectrin, appear to control membrane plasticity and integrity in several cell types. To provide a structural basis for understanding these crucial biological events, we have solved the crystal structure of a complex between bovine calmodulin and the calmodulin-binding domain of human alphaII-spectrin (Protein Data Bank ID code 2FOT). The structure revealed that the entire calmodulin-spectrin-binding interface is hydrophobic in nature. The spectrin domain is also unique in folding into an amphiphilic helix once positioned within the calmodulin-binding groove. The structure of this complex provides insight into the mechanisms by which calmodulin, calpain, caspase, and tyrosine phosphorylation act on spectrin to regulate essential cellular processes.
Structure of the calmodulin alphaII-spectrin complex provides insight into the regulation of cell plasticity.,Simonovic M, Zhang Z, Cianci CD, Steitz TA, Morrow JS J Biol Chem. 2006 Nov 10;281(45):34333-40. Epub 2006 Aug 31. PMID:16945920
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.