Calcium currents and arrhythmias: insights from molecular biology Stephen R Shorofsky, MD, PhD, C.William Balke, MD  The American Journal of Medicine  Volume 110, Issue 2, Pages 127-140 (February 2001) DOI: 10.1016/S0002-9343(00)00586-6

Figure 1 Schematic model of the transmembrane topology of the α1 subunit of the L-type Ca channel. The P loops in each repeat are indicated by the thick lines. [Reproduced with permission from W.B. Saunders Company, Cardiac Electrophysiology, 3rd ed. (147).] The American Journal of Medicine 2001 110, 127-140DOI: (10.1016/S0002-9343(00)00586-6)

Figure 2 Schematic representation of the regulatory subunits and their putative relationship to the α1 subunit of the L-type Ca channel. [Reproduced with permission from W.B. Saunders Company, Cardiac Electrophysiology, 3rd ed. (147).] The American Journal of Medicine 2001 110, 127-140DOI: (10.1016/S0002-9343(00)00586-6)