Figure 6.

ECA1 catalyzed high-affinity Ca²⁺-pumping activity. Ca²⁺ transport into vesicles isolated from the ECA1-transformed mutant K616 was performed as described in Figure 4, except that the free-Ca²⁺ concentration was buffered from 10 to 70 nm. Lineweaver-Burk plot (inset) showed an apparent K_m for Ca²⁺ of 30 ± 10 nm (n = 5).