Ca2+ sensors of L-type Ca2+ channel

Ca2+-induced inactivation of L-type Ca2+ is differentially mediated by two C-terminal motifs of the ale subunit, L (1572-1587) and K (1599-1651) impli cated for calmodulin binding. We found that motif L is composed of a highly selective Ca2+ sensor and an adjacent Ca2+-independent tethering site for calmodulin, The Ca sensor contributes to higher Ca2+ sensitivity of the mot if L complex with calmodulin. Since only combined mutation of both sites re moves Ca2+-dependent current decay, the two-site modulation by Ca2+ and cal modulin may underlie Ca2+-induced inactivation of the channel. (C) 2000 Fed eration of European Biochemical Societies. Published by Elsevier Science B. V, All rights reserved.Ca2+-induced inactivation of L-type Ca2+ is differen tially mediated by two C-terminal motifs of the ale subunit, L (1572-1587) and K (1599-1651) implicated for calmodulin binding. We found that motif L is composed of a highly selective Ca2+ sensor and an adjacent Ca2+-independ ent tethering site for calmodulin, The Ca sensor contributes to higher Ca2 sensitivity of the motif L complex with calmodulin. Since only combined mu tation of both sites removes Ca2+-dependent current decay, the two-site mod ulation by Ca2+ and calmodulin may underlie Ca2+-induced inactivation of th e channel. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.