STRUCTURE AND EVOLUTION OF THE ACTIN CROSS-LINKING PROTEINS

The actin crosslinking proteins exhibit marked diversity in size and shape and crosslink actin filaments in different ways. Amino acid sequence analysis of many of these proteins has provided clues to the origin of their diversity. Spectrin, alpha-actinin, ABP-120, ABP-280, fimbrin, and dystrophin share a homologous sequence segment that is implicated as the common actin binding domain. The remainder of each protein consists of repetitive and non-repetitive sequence segments that have been shuffled and multiplied in evolution to produce a variety of proteins that are related in function and in composition, but that differ significantly in structure.