Effect of ATP analogues on the gorging response of Aedes aegypti

The ATP analogues adenylylimidodiphosphate and adenylylmethylenediphosphate are 3–5‐fold more effective than ATP as gorging stimulants for Aedes aegypti. This increased potency is not due to the fact that the two analogues are not hydrolysed by the mosquito salivary apyrase, but most likely to their greater affinity to the mosquito gustatory receptor protein. The analogues 2'd ATP and 3'd ATP are about half as potent as ATP, while 2′,3′‐dideoxyadenosine triphosphate is 10‐fold more potent than ATP in evoking the gorging response. It is proposed that removal of both hydroxyl groups eliminates binding of the stimulant at the ribose moiety, thus allowing the molecule greater freedom to rotate and bind more effectively to its two other binding sites at the amino group on the purine and at the terminal phosphate. Our data demonstrate that ATP activates the gorging response of Ae.aegypti merely by binding to its receptor protein and is not required as an exogenous source of energy. Gorging response to ATP is competitively inhibited by novobiocin.