INT 9724168 de Lanerolle This U.S.-Czech research project between Primal de Lanerolle of the University of Illinois, Chicago, and Pavel Hozak of the Institute of Experimental Medicine, Prague, will attempt to identify a non-filamentous motor protein, myosin I, by cloning and sequencing the cDNA for it. Their intent is to initiate the process of defining the physiological functions of this protein by using immunogold electron microscopy to identify the structures it associates with in the nucleus. Results of the sequencing will be compared to published sequences for members of the myosin superfamily to determine whether the 120 kDa protein is myosin I, some other unconventional myosin, or a totally new actin, ATP and calmodulin binding ATPase in the nucleus. Central to the effort is an antibody to myosin I, which the U.S. and Czech researchers have produced and affinity purified from bovine adrenal glands. This antibody inhibits the actin-activated ATPase activity of purified adrenal myosin I but not that of purified adrenal myosin II. These antibodies recognize a 120 kDa protein that is larger than the antigen (16 kDa) in the cytoplasm and in the nucleus. Comparative studies using different antibodies to myosin I suggest that these antibodies recognize a unique, previously undescribed myosin I isoform that is an intranuclear actin-based molecular motor. If successful, this research effort to unequivocally identify the 120 kDa protein could make fundamental contributions to our understanding of the cellular functions of myosin and the biology of the cell nucleus. This project in cellular organization fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Central Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence. ??
