Protein phosphatase activity is required for prothoracicotropic hormone-stimulated ecdysteroidogenesis in the prothoracic glands of the tobacco hornworm, Manduca sexta
✍ Scribed by Qisheng Song; Lawrence I. Gilbert
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 919 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0739-4462
No coin nor oath required. For personal study only.
✦ Synopsis
The multiple phosphorylation of ribosornal protein S6 appears to be required for prothoracicotropic hormone (PITH)-stimulated protein synthesis and ecdysteroidogenesis by the prothoracic glands of Manduca sexta. The present study investigated the role of protein phosphatase in these phenomena by analyzing the effects of pretreatment of prothoracic glands with the phosphatase inhibitors okadaic acid and calyculin A in both basal and PITH-stimulated glands. Okadaic acid or calyculin A treatment enhanced ribosomal S6 phosphorylation in control glands to a level similar to that observed with PTTHstimulated glands. This treatment also prevented S6 dephosphorylation but had no apparent synergistic effect on S6 phosphorylation in PITH-stimulated glands. Most importantly, okadaic acid or calyculin A treatment inhibited, rather than augmented, ecdysteroidogenesis in both PTTt i-stimulated and non-stimulated glands. The composite data suggest that protein phosphatase activity sensitive to okadaic acid or calyculin A is required for PnH-stimulated ecdysteroidogenesis.