V-ATPase-energized epithelia and biological insect control

Background is provided for the experimentally detailed contributions concerning the structure, distribution and function of V-ATPase-based ion pumps in insect epithelia. The mode of action of an insecticidal bacterial protein, which is dependent upon the V-ATPase-energized state in larval lepidopteran midgut for activity, is discussed. The nature of the insect electrogenic cation pump Transport studies on insect epithelia led to an early rejection of the vertebrate paradigm of a Na+/K+-ATPase as the primary transducer of energy from chemical bonds to electrochemical ion gradients. More than twenty years ago Keynes (1969) proposed that a unique ion pump existed in insect gastrointestinal epithelia, and possibly in the stria vascularis as well as a few other highly specialized vertebrate tissues, which transported potassium ions electrogenically out of the cells, causing the output side to become electrically positive. The pump was found in the typical columnar epithelial cells of Malpighian tubules as well as in more specialized secretory cells of salivary glands and midgut. The only distinguishing features of cells that contained this pump seemed to be the presence of F|-ATPase-like projections, later named portasomes (Harvey, 1980), o