A dynamic positive feedback mechanism, known as 'facilitation', augments L-type calcium-ion currents (I(Ca)) in response to increased intracellular Ca2+ concentrations. The Ca2+-binding protein calmodulin (CAM) has been implicated in facilitation, but the single-channel signature and the signalling events underlying Ca2+/CaM-dependent facilitation are unknown. Here we show that the Ca2+/CaM-dependent protein kinase II (CaMK) is necessary and possibly sufficient for I(Ca) facilitation. CaMK induces a channel-gating mode that is characterized by frequent, long openings of L-type Ca2+ channels. We conclude that CaMK-mediated phosphorylation is an essential signalling event in triggering Ca2+/CaM-dependent I(Ca) facilitation.
ASJC Scopus subject areas
- Cell Biology