A new member of acid-sensing ion channels from pituitary gland

Acid-sensing ion channels (ASICs) constitute a branch of the super-gene fam ily of amiloride-sensitive sodium channels. So far five different ASICs hav e been cloned from mammalian tissues. They are activated by a drop of extra cellular pH but differ with respect to effective agonist concentration, des ensitization and mRNA expression pattern. Here we report cloning of ASIC4, a new protein showing about 45% identity to other ASICs. ASIC4 is 97% ident ical between rat and human and shows strongest expression in pituitary glan d. Moreover, we detected expression throughout the brain, in spinal cord, a nd inner ear. ASIC4 cannot be activated by a drop of extracellular pH in Xe nopus oocytes, suggesting association with other subunits or activation by a ligand different from protons. Our results suggest a role for ASICs also in endocrine glands. NeuroReport 11:1607-1611 (C) 2000 Lippincott Williams & Wilkins.