Vinculin is a cytoskeletal protein which localizes to adherens junctions that occur between adjoining cells. A muscle-specific splice variant metavinculin is identical in sequence to vinculin with the exception of a 68-residue insert within its C-terminal domain. Two mutations (R975W and L954del) within this insert have been associated with the onset of dilated cardiomyopathy. This study investigated structural differences among the wild-type and mutant metavinculin tail domains, and also examined differences in binding characteristics among known ligands. Structural studies indicated that the mutations do not induce large conformational changes on the metavinculin tail, though they may result in reduced exposed hydrophobie surface, and the R975W mutant was found to show slightly decreased thermal stability. Interactions of wild-type and mutant proteins with the vinculin head, acidic phospholipids, EVH1, and actin were shown to be similar. In addition, viscometric analysis indicated a synergistic effect of vinculin-metavinculin heterodimerization on filamentous actin network formatio
