Non-requirement of a regulatory subunit of Protein Phosphatase 2A, PP2A-B', for activation of Sex comb reduced activity in Drosophila melanogaster.
The Drosophila HOX transcription factor, Sex combs reduced (SCR), is required for determining labial and the first thoracic segmental identity. A Protein Phosphatase 2A holoenzyme assembled with the PP2A-B' regulatory subunit is proposed to specifically interact with, and dephosphorylate, the SCR homeodomain activating SCR protein activity. To test this hypothesis further, a null mutation was created in the PP2A-B' gene, PP2A-B'(Delta), using Flip-mediated, site-specific recombination. The number of sex comb bristles, salivary gland nuclei and pseudotracheal rows are SCR-dependent and were counted as a measure of SCR activity in vivo. Adults and larvae homozygous for PP2A-B'(Delta) showed no decrease in SCR activity. In addition, no evidence of functional redundancy of PP2A-B' with other regulatory subunits, Twins (TWS) and Widerborst (WDB), for dephosphorylation and activation of SCR activity was observed. In conclusion, a PP2A holoenzyme containing the PP2A-B' regulatory subunit has no role in the dephosphorylation and activation of SCR, and analysis of functional redundancy of PP2A regulatory subunits uncovered no evidence supporting a role of PP2A activity in dephosphorylation and activation of SCR.
Moazzen
Hoda
H
Department of Biology, University of Western Ontario, 1151 Richmond St., London, Ontario, Canada.
Rosenfeld
Robyn
R
Percival-Smith
Anthony
A
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism; D006720:Homozygote; D008297:Male; D008957:Models, Genetic; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D012469:Salivary Glands / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; C059627:Scr protein, Drosophila; D014157:Transcription Factors; D054648:Protein Phosphatase 2