Processing and distributions of dec-1 eggshell products in Drosophila melanogaster
The Drosophila eggshell dec-1 gene offers a good opportunity to study the role of regulated proteolysis in the assembly of a complex extracellular structure. The dec-1 locus generates proteins of 106 kDa (fc106), 125 kDa (fc125), and 177 kDa (fc177). Previous studies established that fc106 is first processed into a protein of approximately 80 kDa, which in turn, is cleaved into a C-terminal derivative of approximately 60 kDa (s60). Preliminary observations indicated that fc125 may also be processed during oogenesis. Polyclonal antibodies produced against trpE-fusion proteins containing selected regions of dec-1 ORF were used to further analyze the proteolytic processing of the dec-1 proteins as well as their in situ distribution in the eggshell. It was found that fc106, fc125 and fc177 follow different regulated maturation pathways that result in the production of several stable proteins with distinctive N- and C-termini. Each one of the dec-1 mature proteins shows a different distribution in the eggshell. fc106 processing generates three final products, the previously identified s60, a 25 kDa (s25) and a 20 kDa (s20) proteins. s60, fractionates between the vitelline membrane (VM) and the chorion, the two main layers of the eggshell; s25 is a chorion component while s20 localizes into vesicles inside the oocyte. fc125 processing yields a stable protein of approximately 95 kDa which during early choriogenesis is observed in the VM and in the forming chorion. THe final processing derivative of fc177 localizes in the mature eggshell, inside rounded cavities characteristics of the shell chorion. The different behavior in the egg chamber of the various mature dec-1 proteins suggest that there is no functional redundancy among them.
Maria Isabel Nogueron,
"Processing and distributions of dec-1 eggshell products in Drosophila melanogaster"
(January 1, 1996).
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