Figure 2.

Annexin-Enriched Preparation Elevates [Ca²⁺]_cyt in Arabidopsis Root Epidermal Protoplasts.

(A) Increase in [Ca²⁺]_cyt. An annexin-enriched preparation added (arrow) to the extracellular membrane face of Arabidopsis root epidermal protoplasts (constitutively expressing aequorin) caused a touch-induced transient increase in [Ca²⁺]_cyt followed by a more sustained, dose-dependent increase (top and middle panels). Preincubation with 0.1 mM GdCl₃ abolished the response (bottom panel).

(B) Effect of channel blockers on the increase in [Ca²⁺]_cyt. Mean ± se peak transient [Ca²⁺]_cyt responses from 5 mg/L annexin preparation with 10 mM external Ca²⁺. Channel blockers were incorporated at 0.1 mM (n = 5).

(C) Dose dependency of mean ± se peak transient [Ca²⁺]_cyt response and apparent steady state basal [Ca²⁺]_cyt. Basal [Ca²⁺]_cyt was determined 7 to 10 min after the end of the transient (n = 4).