CHARACTERIZATION OF ACIDIC RIBOSOMAL-PROTEINS FROM 3 DEVELOPMENTAL STAGES OF THE MEDFLY CERATITIS-CAPITATA

Acidic proteins extracted with 0.5 M NH4Cl and 50% ethanol from riboso mes of the medfly Ceratitis capitata showed two major bands of MW 15 a nd 17 kD after SDS electrophoresis. Isoelectrofocusing of acidic prote ins resolved two groups of bands at pH 4.5 and 3.5. Similar patterns w ere observed both from the acidic ribosomal protein fraction and from total ribosomes, treated with RNase. Treatment with alkaline phosphata se reduced the number of bands with a shift to a higher pI, indicating dephosphorylation. The phosphorylation pattern of the acidic proteins changed at three different stages of development, six day larvae, whi te pupae and 0-2 days old embryos. The two protein groups correspond t o multi-phosphorylated forms of eucaryotic acidic ribosomal proteins P 1 and P2. This was shown by immunoblotting with specific monoclonal an tibodies.