[ANK1_HUMAN] Defects in ANK1 are a cause of spherocytosis type 1 (SPH1) [MIM:182900]; also called hereditary spherocytosis type 1 (HS1). Spherocytosis is a hematologic disorder leading to chronic hemolytic anemia and characterized by numerous abnormally shaped erythrocytes which are generally spheroidal. Inheritance can be autosomal dominant or recessive.
[ANK1_HUMAN] Attaches integral membrane proteins to cytoskeletal elements; binds to the erythrocyte membrane protein band 4.2, to Na-K ATPase, to the lymphocyte membrane protein GP85, and to the cytoskeletal proteins fodrin, tubulin, vimentin and desmin. Erythrocyte ankyrins also link spectrin (beta chain) to the cytoplasmic domain of the erythrocytes anion exchange protein; they retain most or all of these binding functions. Isoform Mu17 together with obscurin in skeletal muscle may provide a molecular link between the sarcoplasmic reticulum and myofibrils.
Ankyrins are multifunctional adaptors that link specific proteins to the membrane-associated, spectrin- actin cytoskeleton. The N-terminal, 'membrane-binding' domain of ankyrins contains 24 ANK repeats and mediates most binding activities. Repeats 13-24 are especially active, with known sites of interaction for the Na/K ATPase, Cl/HCO(3) anion exchanger, voltage-gated sodium channel, clathrin heavy chain and L1 family cell adhesion molecules. Here we report the crystal structure of a human ankyrinR construct containing ANK repeats 13-24 and a portion of the spectrin-binding domain. The ANK repeats are observed to form a contiguous spiral stack with which the spectrin-binding domain fragment associates as an extended strand. The structural information has been used to construct models of all 24 repeats of the membrane-binding domain as well as the interactions of the repeats with the Cl/HCO(3) anion exchanger and clathrin. These models, together with available binding studies, suggest that ion transporters such as the anion exchanger associate in a large central cavity formed by the ANK repeat spiral, while clathrin and cell adhesion molecules associate with specific regions outside this cavity.
Crystal structure of a 12 ANK repeat stack from human ankyrinR.,Michaely P, Tomchick DR, Machius M, Anderson RG EMBO J. 2002 Dec 2;21(23):6387-96. PMID:12456646
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