Hearing loss and vestibular deficiencies frequently are the result of genetic defects of environmental damage targeting the hair cells in the inner ear. The apical hair cell is composed of actin-filled stereocilia, within which the transduction channels are housed. Myosin 1c (Myo1c), has been identified as an adaptation motor near the tips of the stereocilia. Tip-links connect each stereocilia to its next tallest neighbor and tip-link tension influences the transduction channel open state. Myo1c's role is to reset channel open probability through modulating resting tension of the tip-link following deflection of the hair bundle. The drive of this study is to understand the influence of Protein Kinase A (PKA) phosphorylation on the ability of Myo1c to regulate transduction force production, and open probability. PKA phosphorylation of Myo1c is likely to affect the function of Myo1c, due to the target site's location at a proposed flexible region of the myosin. A change in Myo1c dynamics is likely to have major consequences for transduction open probability in the hair cell. Using biochemical characterization, including in vitro motility and ATPase assays, and immunoprecipitation of Myo1c, the importance of PKA phosphorylation of Myo1c will be determined. ? ?
