F-actin cross-linking protein is thought to anchor actin to a variety of intracellular structures. This is a bundling protein. Homodimer; antiparallel (By similarity). Interacts with PDLIM4 (via PDZ domain) (PubMed:14729062). Isoforms only differ in the region of the first EF-hand calcium-binding motif. Belongs to the alpha-actinin family.