FIGURE 6.

Transferring the luminal tail of SLN to a generic transmembrane helix. A, topology model of Leu₉ and Leu₉tail (white, cytosolic residues; gray, transmembrane residues; black, luminal residues). K_Ca (B) and V_max (C) values were determined from ATPase activity measurements for SERCA in the absence and presence of Leu₉ and Leu₉tail. For comparative purposes, the black lines indicate the values for SERCA alone, and the gray lines indicate values for SERCA in the presence of wild-type SLN. Notice that Leu₉tail closely recapitulates wild-type SLN. Each data point is the mean ± S.E. (error bars) (n ≥ 4). The V_max, K_Ca, and n_H are given in Table 1. Asterisks indicate comparisons against wild-type SLN (p < 0.05).