Detection of metavinculin in human platelets using a modified talin overlay assay.

Talin was purified from human platelets and proteolytically cleaved by the calcium-dependent protease (CDP II) to two stable fragments of 200 and 47 kDa. The 200 kDa fragment was radiolabeled and used in Western blot overlay assays of fractionated platelet proteins. This procedure revealed vinculin to be the major talin binding protein. However, in addition, a less abundant protein of approximately 150 kDa also interacted strongly with the talin fragment. Using conventional immunoblot analysis we have confirmed that this protein is metavinculin, a protein previously believed to be confined to cardiac and smooth muscle tissue.