An Investigation of the Role of the Amino and Carboxyl Terminal Regions of Flightin and Their Contributions to Thick Filament Properties in Drosophila Flight Muscle
The University of Vermont
The protein Myosin is paramount for the generation of force by muscle cells. While there is a wealth of information regarding the mechanisms and functions of this protein's motor head domain, there is a substantial knowledge gap surrounding myosin's rod domain. Though it has been implicated in the formation and elongation of myosin, the means through which this coiled-coil rod interacts with associated proteins in the assembly of a muscle cell's thick filaments is not fully understood. Flightin, a myosin binding protein expressed in the Indirect Flight Muscles of Drosophila, is known to influence the regulation of thick filament length and rigidity, properties that directly impact flight ability. Analysis of flightin's amino acid sequence revealed three distinct regions, each of which express varying degrees of evolutionary conservation; a highly conserved 'WYR' middle region and variable amino and carboxy terminal regions. While previous studies have shown that a removal of the amino and carboxy terminal regions of flightin result in a reduction in the organization and functionality of Drosophila flight muscle on a macroscopic scale, the direct contributions of these regions to sub-cellular muscular components remains unknown. Building upon prior investigations, Atomic Force Microscopy was used to examine each region of flightin and test the hypothesis that they represent three independent functional domains. This study will help to validate that the WYR region is the locus of the myosin- binding domain necessary for the incorporation of flightin in thick filaments. Furthermore this investigation will determine whether the amino or carboxy terminal regions are responsible for the regulation of thick filament length and compliance. This procedure will encourage research and further the understanding of proteins that may be structurally or functionally similar to flightin, such as the cardiac myosin binding protein-c, which allows for proper cardiac function in humans.