The long term goals are to determine the molecular structure of the outer arm of the Chlamydomonas flagellum, and to elucidate the functions of the individual subunits and polypeptide chains of its dynein ATPases. The alpha and beta subunits of 18S dynein will be characterized by electron microscopy to determine their relationship to the whole 18S particle, and the beta subunit subfractionated to learn more about its individual chains and their relationship to one another. New monoclonal antibodies specific for the dynein chains will be developed; these and others previously obtained will be used to determine the locations of the chains in the arm in situ and in the isolated dyneins, to identify the structural domains involved in binding of dynein to microtubules, to investigate the functions of the three outer arm dynein ATPases, and to clarify the relationships between the dyneins of different species. The sites of ATP binding will be located on the isolated dynein particles by electron microscopic techniques, mapped on the individual dynein chains by biochemical techniques, and characterized by analysis of proteolytic fragments. The epitopes recognized by various monoclonal antibodies will also be mapped on the individual chains. Mutants with abnormalities in the outer arm will be studied to learn more about the assembly and function of the arm, and to investigate the possibility that non-dynein ATPases are present in the axoneme. The dynein arms generate the forces that are the basis for motility in all eukaryotic cilia and flagella, including those of man; consequently, knowledge obtained from these studies will increase our understanding of those human diseases and genetic abnormalities, such as Kartagener's syndrome, that affect the arms. The studies will also provide a basis for understanding such important processes as sperm maturation and capacitation, which involve changes in the functioning of the arms, and chromosome movement in dividing cells, which also appear to involve dynein-like ATPases.
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