TASK is a member of the TWIK-related (two P-domain) K+channel familyidentified in human tissues []. It is widely distributed, being particularly abundant in the pancreas and placenta, but it is also found inthe brain, heart, lung and kidney. Its amino acid identity to TWIK-1 and TREK-1 is rather low, being about 25-28%. However, it is thought to share the same topology of four TM segments, with two P-domains. TASK is very sensitive to variations in extracellular pH in the physiological range, changing from fully-open to closed in approximately 0.5 pH units around pH 7.4. Thus, it may well be a biological sensor of external pH variations.Potassium channel subfamily K member 3 (KCNK3, also known as TASK-1) was the first member of the TASK family to be cloned. It is widelydistributed, being particularly abundant in the pancreas and placenta, but is also found in the brain, heart, lung and kidney. In addition to the maintenance of the resting membrane potential, it is also involved in K+ transport associated with recycling/secretion and the modulation of electrical activity of excitable cells [].
