ATPases are a class of enzymes that catalyze ATP hydrolysis to dephosphorylate adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and release energy through active transport. There are different types of ATPases: (1) Vacuolar-type H+-ATPases (V-ATPases), which are found within the membranes of many organelles, such as endosomes, lysosomes, and secretory vesicles in eukaryotic cells, and which catalyze ATP hydrolysis to proton transport across intracellular and plasma membranes. In nervous system, V-ATPase acidifies synaptic vesicles to release chemicals (neurotransmitters) for neuronal signal communication between the nervous cells. They are also found in the plasma membranes of a wide variety of cells such as intercalated cells of the kidney, osteoclasts (bone-resorbing cells), macrophages, neutrophils, sperms, and certain tumor cells. (2) Plasma membrane H+-ATPases, P-ATPases (E1E2-ATPases), which are found in bacteria, fungi, eukaryotic plasma membranes, and organelles, function to transport a variety of different ions across membranes. An important example of food digestion is the hydrogen–potassium transporter (H+/K+ATPase or gastric proton pump) that acidifies the contents of the stomach by pumping hydrogen ion into the stomach.
This handbook presents the scope of vacuolar H+-ATPases and plasma membrane H+-ATPases through contributions by leading experts in the area of basic science and clinical medicine. Their expertise in biochemistry, cell biology, and pathophysiology has greatly added to bring forth the most recent results to our readers. This book is the first of its kind to summarize an essential link between vacuolar H+-ATPase and the glycolysis metabolic pathway that helps to understand the mechanism of diabetes and the metabolism of cancer cells. This book presents recent findings on the structure and function of vacuolar H+-ATPase in glucose-promoting assembly and in glucose signaling, in addition to describing the regulatory mechanisms of vacuolar H+-ATPase in yeast cells, neural stem cells, kidney cells, cancer cells, as well as under diabetic conditions. This book also provides information pertaining to the role of V-ATPase on insulin secretion and cancer chemotherapy. It also illustrates the activation of plasma membrane H+-ATPase through glucose-induced calcium signaling in Saccharomyces cerevisiae yeast cells.