Schematic of the structure, membrane topology, and generalized relative functional contributions of individual structural elements in BKγ subunits. The structural models of the LRRDs were built as described previously (Yan and Aldrich, 2012). The different colors indicate the structural elements’ relative contributions (in millivolts) to the BKγ subunit–induced shifts of voltage dependence of BK channel activation. “Reference” means “being used as a reference for comparison,” and “negligible” means “can be deleted without influence on modulatory function.”