α-Actinin 4 also known as Actinin alpha 4, ACTN4 is a member of the spectrin gene family, which encodes a diverse group of cytoskeletal proteins, including spectrins, dystrophins, and α-actinins. α-actinin 4 is primarily located in the cytoskeleton of muscle and non-muscle cells, such as skeletal, cardiac, and smooth muscle cells, where α-actinin 4 plays a vital role in maintaining cellular structure and integrity. The unique structure of α-actinin 4, which includes one actin-binding domain, two calponin-homology domains, two EF-hand domains, and four spectrin repeats, allows α-actinin 4 to function effectively as a bundling protein that cross-links filamentous actin (F-actin), anchoring F-actin to various intracellular structures. This anchoring is essential for cellular processes such as muscle contraction and cell signaling.