Vinculin is a eukaryotic protein that seems to be involved in the attachment of the actin-based microfilaments to the plasma membrane. Vinculin is located at the cytoplasmic side of focal contacts or adhesion plaques.[1] In addition to actin, vinculin interacts with other structural proteins such as talin and alpha-actinins.
Vinculin is a large protein of 116 kDa (about a 1000 residues). Structurally the protein consists of an acidic N-terminal domain of about 90 kDa separated from a basic C-terminal domain of about 25 kDa by a proline-rich region of about 50 residues. The central part of the N-terminal domain consists of a variable number (3 in vertebrates, 2 in Caenorhabditis elegans) of repeats of a 110 amino acids domain.
Alpha-catenins are evolutionary related to vinculin.[2] Catenins are proteins that associate with the cytoplasmic domain of a variety of cadherins. The association of catenins to cadherins produces a complex which is linked to the actin filament network, and which seems to be of primary importance for cadherins cell-adhesion properties. Three different types of catenins seem to exist: alpha, beta, and gamma. Alpha-catenins are proteins of about 100 kDa which are evolutionary related to vinculin. In terms of their structure the most significant differences are the absence, in alpha-catenin, of the repeated domain and of the proline-rich segment.