Flagellar Glycoprotein Dynamics and Whole Cell Locomotion

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The goal of this research is to understand the mechanism involved in force transduction occurring at the cell surface that is responsible for whole cell locomotion. The movement of flagellar membrane glycoproteins (in particular, a pair of 350 kDa concanavalin A-binding glycoproteins) within the plane of the flagellar membrane are involved in the whole cell gliding locomotion exhibited by the eukaryotic algal cell Chlamydomonas. Crosslinking of the flagellar membrane glycoproteins triggers a transmembrane signaling pathway that activates intraflagellar machinery responsible for movement of the 350 kDa glycoproteins within the plane of the flagellar membrane. Experiments are proposed to analyze the roles of calcium, cAMP, cGMP and protein phosphorylation in the transmembrane signaling pathway in the flagellum. It will be determined whether crosslinking of flagellar surface glycoproteins is necessary to activate the transmembrane signaling pathway and whether the crosslinking results in a tighter association of flagellar membrane glycoproteins with the underlying cytoskeleton (axoneme). Experiments are proposed to develop an in vitro model system for reactivating flagellar surface motility and to exploit such a system to understand the transmembrane signaling the generation of force for glycoprotein movement. Efforts will be made to identify and characterize the components of the motor responsible for flagellar membrane glycoprotein dynamics and gliding motility. Understanding the mechanisms by which cells control the distribution of plasma membrane proteins and by which they actively change the distribution of these proteins will have significance for understanding the functioning of higher organisms as well as unicellular algae.