Different effects of the Ca2+-binding protein, KChIP1, on two Kv4 subfamily members, Kv4.1 and Kv4.2

The Ca2+-binding protein, K+ channel-interacting protein 1 (KChIP1), modula tes Kv4 channels. We show here that KChIP1 affects Kv4.1 and Kv4.2 currents differently. KChIP1 slows Kv4.2 inactivation but accelerates the Kv4.1 ina ctivation time course. Kv4.2 activation is shifted in a hyperpolarizing dir ection, whereas a depolarizing shift occurs for Kv4,1, On the other hand, K ChIP1 increases the current amplitudes and accelerates recovery from inacti vation of both currents, An involvement of the Kv4 N-terminus in these diff erential effects is demonstrated using chimeras of Kv4.2 and Kv4.1, These r esults reveal a no, el interaction of KChIP1 with these two Kv4 members. Th is represents a mechanism to further increase the functional diversity of K + channels. (C) 2001 Federation of European Biochemical Societies. Publishe d by Elsevier Science B.V. All rights reserved.