ATP and ADP modulate a cation channel formed by Hsc70 in acidic phospholipid membranes

Abstract

Heat shock proteins are molecular chaperones that participate in different cellular processes, particularly the folding and translocation of polypeptides across membranes. In this regard, members of the Hsp70 family of heat shock proteins have been observed in close proximity to cellular membranes. In this study, the direct interaction between Hsc70, which is constitutively expressed in cells, and lipid membranes was investigated. Recombinant Hsc70 was incorporated into artificial lipid bilayers, and a transmembrane ion flow was detected, suggesting the incorporation of an ion pathway. This ion flow was very stable and occurred in well defined, multilevel discrete electrical current events, indicating the formation of a multiconductance ion channel. The Hsc70 channel activity is ATP-dependent and is reversibly blocked by ADP. This channel has cationic selectivity. Thus, Hsc70 can directly interact with lipid membranes to create functionally stable ATP-dependent cationic pathways.