BARBARA ANN WIBLE, Marquette University


The mechanisms regulating gene expression during development and in different tissues are of utmost interest and importance in molecular genetics today. Muscle proteins and their appearance during the course of muscle development are well suited for this type of study because they are coordinately regulated, and, therefore, their structural genes must be able to respond to the same regulatory signals. One muscle protein, myosin, has been extensively characterized as a polymorphic multisubunit protein in vertebrate systems. Unfortunately, however, these systems are not readily amenable to the genetic analysis that could yield much information regarding the ultimate control of gene expression. Therefore, this study of myosin from two developmental stages of Drosophila melanogaster, an organism suited to genetic manipulation, was performed. Myosin was characterized biochemically from two developmental stages of Drosophila melanogaster: larval and adult. A number of techniques were variously employed in the purification of myosin including ammonium sulfate fractionation and several chromatographic methods (ion exchange, affinity, hydroxyapatite, and molecular exclusion). The three myosin ATPase activities (Ca('++), K('+)-EDTA, and Mg('++)) were characterized, and the parameters K(,M), V(,max), and pH optimum, as well as thermal denaturation profiles and the effects of small molecules on ATPase activities were determined. The myosins were examined electrophoretically by denaturing (SDS) and nondenaturing polyacrylamide gel electrophoresis. With these methods myosin from larvae and adults was shown to differ in ATPase activities, putative light chain content, and heavy chain composition. Peptide mapping of the adult and larval myosin heavy chains using the proteolytic enzyme papain suggested sequence differences between the two proteins. These results are discussed in light of the recent reports in the literature of the existence of a single myosin heavy chain gene in the Drosophila genome, and the implications for the possible type of genetic regulation occurring in Drosophila muscle development are discussed.

Recommended Citation

WIBLE, BARBARA ANN, "BIOCHEMICAL CHARACTERIZATION OF MYOSIN IN DROSOPHILA MELANOGASTER" (1983). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. AAI8410846.