Role of Cyclic Nucleotides in Hormone Action

Smith, Wendy A.; Combest, Wendell L.

doi:10.1016/b978-0-08-030809-8.50014-9

Cited by 1 publication

(1 citation statement)

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“…The work extends the range of insect proteins for which covalent modification has been ascribed a role in modulation of activity [14,15]. Of relevance is a report for CaZZiphora fat body that treatments expected to result in changes in intracellular concentrations of CAMP lead to modulation of ecdysone 20-monooxygenase [27].…”

Section: Discussionmentioning

confidence: 94%

Possible role for covalent modification in the reversible activation of ecdysone 20‐monooxygenase activity

Hoggard¹,

Fisher²,

Rees³

1989

Arch Insect Biochem Physiol

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Evidence is presented for the reversible activation-inactivation of the microsoma1 ecdysone 20-monooxygenase from fat body of the cotton leafworm, Spodoptera littoralis, in a manner commensurate with reversible changes in its phosphorylation state. The activity of the monooxygenase was higher following preincubation with fluoride (an inhibitor of phosphoprotein phosphatases) than in its absence. Preincubation with alkaline phosphatase o r with CAMP-dependent protein kinase resulted in appreciable diminution or enhancement, respectively, in monooxygenase activity. Activation of ecdysone 20-monooxygenase activity could also be effected by incubation with a cytosolic fraction in the presence of CAMP, ATP, and fluoride; this activation was prevented by a CAMP-dependent protein kinase inhibitor. Similarly, inactivation of the monooxygenase was achieved by preincubation with cytosol, the effect being enhanced by Ca2+-calmodulin or by M g f ions. The combined results provide indirect evidence that the microsomal ecdysone 20-monooxygenase exists in an active phosphorylated form and an inactive dephosphorylated form, interconvertible by a CAMP-dependent protein kinase and a phosphoprotein phosphatase.

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Section: Discussionmentioning

confidence: 94%