Parvin, a 42 kDa focal adhesion protein, related to the α-actinin superfamily

ABSTRACT We have identified and cloned a novel 42-kDa protein termed α-parvin, which has a single α-actinin-like actin-binding domain. Unlike other members of the α-actinin superfamily, which are large multidomain proteins, α-parvin lacks a rod domain or any other C-terminal structural modules and therefore represents the smallest known protein of the superfamily. We demonstrate that mouse α-parvin is widely expressed as two mRNA species generated by alternative use of two polyadenylation signals. We analyzed the actin-binding properties of mouse α-parvin and determined the Kd with muscle F-actin to be 8.4±2.1 μM. The GFP-tagged α-parvin co-localizes with actin filaments at membrane ruffles, focal contacts and tensin-rich fibers in the central area of fibroblasts. Domain analysis identifies the second calponin homology domain of parvin as a module sufficient for targeting the focal contacts. In man and mouse, a closely related paralogue β-parvin and a more distant relative γ-parvin have also been identified and cloned. The availability of the genomic sequences of different organisms enabled us to recognize closely related parvin-like proteins in flies and worms, but not in yeast and Dictyostelium. Phylogenetic analysis of α-parvin and its para- and orthologues suggests, that the parvins represent a new family of α-actinin-related proteins that mediate cell-matrix adhesion.