Phosphorylation

Definition

The enzymatic transfer of a phosphate group from a donor molecule—typically ATP—to a target substrate, thereby altering its structure, activity, or binding properties. In arthropods, phosphorylation serves as a primary molecular switch regulating metabolic enzymes, ion channels, and transcription factors; it underlies rapid physiological responses such as flight muscle activation, diapause entry and termination, and ecdysteroid signaling during molt cycles.

Etymology

From phosphor- (phosphorus) + -yl (chemical radical) + -ation (process), referring to the addition of a phosphoryl group (PO₃²⁻).

Example

During insect flight, phosphorylation of glycogen phosphorylase by protein kinase A triggers glycogenolysis, rapidly mobilizing glucose-1-phosphate to fuel sustained wing-beat muscle contraction.

Related Terms

• kinase
• phosphatase
• ATP
• signal transduction
• metabolism
• protein kinase A
• glycogenolysis

Usage Notes

Distinguished from phosphor-ylation (archaic spelling) and from broader 'phosphorylation cascades'—sequential multi-step regulatory pathways common in hormone signaling (e.g., juvenile hormone and ecdysone pathways). Reversible; opposing dephosphorylation by phosphatases allows fine-tuned control. In entomological toxicology, disruption of phosphorylation (e.g., by organophosphate insecticides targeting acetylcholinesterase) has lethal physiological consequences.