In skeletal muscle, required for costamere localization of DMD and betaDAG1 (By similarity). Membrane-cytoskeleton linker. May participate in the maintenance/targeting of ion channels and cell adhesion molecules at the nodes of Ranvier and axonal initial segments. Regulates KCNA1 channel activity in function of dietary Mg(2+) levels, and thereby contributes to the regulation of renal Mg(2+) reabsorption (PubMed:23903368). May be part of a Golgi-specific membrane cytoskeleton in association with beta-spectrin. Directly interacts with DMD and betaDAG1. This interaction does not interfere with binding between DMD and betaDAG1. It is also required for DMD and betaDAG1 retention at costameres (By similarity). Interacts (via N-terminal ANK repeats) with SCHIP1 isoform 5 (via C-terminus); this interaction is required for the localization at axon initial segments (AISs) and nodes of Ranvier (NRs) (By similarity). May be a constituent of a NFASC/NRCAM/ankyrin G complex. Interacts with RHBG (PubMed:15611082). Interacts with PLEC and FLNC (PubMed:21223964). Interacts with KCNA1; this inhibits channel activity (PubMed:23903368). Interacts (via ANK repeats) with IQCJ-SCHIP1; required for IQCJ-SCHIP1 localization at axon initial segments (AIS) and nodes of Ranvier (PubMed:25950943). Interacts with SCHIP1 (PubMed:25950943). Interacts with SCN5A (PubMed:15579534). In skeletal muscle, localized at costameres and neuromuscular junctions. In macrophages, associated with lysosomes. Expressed in brain, neurons, muscles and other tissues. Up-regulated during muscle cell differentiation. The tandem configuration of the two ZU5 and the UPA domains forms a structural supramodule termed ZZU. ZU5-1 mediates interaction with beta-spectrin, and the ZU5-1/UPA interface is required for ankyrin's function other than binding to spectrin (By similarity). Genetic variations in ANK3 may be associated with autism spectrum disorders susceptibility. The disease is caused by variants affecting the gene represented in this entry. A homozygous deletion in ANK3 predicted to result in frameshift and premature truncation, has been shown to be the cause of moderate intellectual disability, an ADHD-like phenotype and behavioral problems in a consanguineous family (PubMed:23390136). Avidly binds beta spectrin. Ankyrin entry