Dynein is a protein which "powers" the translocation of molecules along microtubules. Dynein is responsible for ciliary and flagellar beating, organelle transport (including axonal transport), and aspects of mitotic anaphase motion. Distinct isoforms of dynein are thought to perform each of these functions. It is hypothesized that dynein is the composite of motor domains that are common to all dyneins and tether domains that are unique to each isoform and that define the location of the isoform and link the dynein to the molecule that is translocated along the microtubule. The long term objective of this project is to determine the structures of dynein isoforms that are expressed in the developing sea urchin embryo, an excellent system for the study of dynein isoforms. The complete sequence of sea urchin axonemal dynein beta heavy chain has recently been determined. The goals of the current three year project are to produce a library of monoclonal antibodies to selected epitopes along the length of the beta chain, to use the antibodies to determine what epitopes are exposed on the surface of the native dynein molecule, and to begin the exploration of isoform-specific epitopes. This project will provide new information that is critical for the elucidation of the molecular mechanism of dynein activity, and will lead to an eventual understanding of the structural basis for dynein isoform functional diversity.
