In neurons, β2-adrenergic (β2AR) enhancement of the activity of L-type voltage-gated calcium channels (Cav1.2) is important for certain forms of synaptic plasticity. The mechanism of regulation is thought to involve phosphorylation by protein kinase A (PKA) of residues in the C-terminus of Cav1.2. A PKA-anchoring protein (AKAP) is required for efficient phosphorylation and enhancement of Cav1.2 channel activity. Neuronally-localized AKAP79, unlike all other AKAPs, binds the Ca2+/calmodulin-activated phosphatase calcineurin (CaN), and thus anchors CaN along with PKA within the Cav1.2-β2AR complex. To study β2AR enhancement of Cav1.2 channel activity, we have used whole-cell patch-clamp to voltage-clamp currents from tsA-201 cells transfected with constructs for full-length Cav1.2, the channel's accessory subunits (β2b, α2δ), AKAP79 and the β2AR. With this system, we have found that β2AR agonist (isoproterenol, Iso) can enhance Ba2+ current ∼25%. Enhancement by Iso was nearly absent (∼5%) when current was carried by Ca2+. Candidates that could support Ca2+-dependent suppression of enhancement include CaN and the Ca2+/calmodulin-dependent kinase CaMKII, which is also scaffolded to the channel. Sites phosphorylated by PKA and suspected of involvement in enhancement include residues S1700, T1704 and S1928 in the CaV1.2 C-terminus. Substitution of alanine at any of these three sites of phosphorylation by PKA abolished enhancement by Iso. To further investigate the mechanism of enhancement, we used the ratio of Ba2+ tail current (−60 mV) to gating charge at reversal as an index of the efficiency of channel opening (Itail/Qgate coupling efficiency). For wild-type (WT) channels, coupling efficiency was increased by Iso. Phosphorylation site mutations (S1700, S1928, S1700+T1704) decreased coupling efficiency in the absence of Iso, and abolished the Iso-induced increase in coupling efficiency observed for WT channels, consistent with the inability of agonist to enhance current carried by the mutants.