332a Monday, February 17, 2014

摘要: Is There a Contribution of Both Cav1.4 and Cav1.3 L-Type Calcium Channels to Retinal Synaptic Transmission? Page 1 Ca2+-free CaM (apoCaM) first bind to channels (preassociate), even before Ca2+ elevation. Subsequent Ca2+ binding to this ’resident’ CaM then induces CDI; channels lacking preassociated apoCaM cannot undergo CDI. Here, using a novel generator of step increases in apoCaM, we find that apoCaM binding has another powerful effect. As shown below, apoCaM elevation not only heightens CDI as expected, but strongly boosts peak Ca2+ current (confirmed to increase PO in single-channel assays). This latter effect could result from the binding of a second CaM to channels, atop the CaM required for CDI. However, plotting normalized peak current as a function of CDI strength invariably resolves a single relationship, over multiple experiments and conditions. This invariance furnishes …