Figure 2.

Functional expression of HvZiP5 (A) and Hvirt1 (B) in Δzrt1Δzrt2 yeast cells. The concentration-dependent Zn uptake was determined by measuring ⁶⁷Zn uptake rates over a range of substrate concentrations during a period of 15 min. Yeast media as described elsewhere (Pedas et al. 2009)¹³ with either 50 mM succinic acid/Tris base pH 4.2 (open symbols) or 5.5 (filled symbols) with varying ⁶⁷Zn concentrations were added HvZIP5, HvIRT1 or pFL6.1 transformed yeast cells to an OD₆₀₀ of 0.75. After the uptake period, the yeast cells were washed three times with ice-cold water, freeze dried, weighed, and acid digested in a microwave oven (multiwave 3000, software version 1.24, Anton Paar GmbH, Graz, Austria). The samples were subsequently diluted with ultra-pure water (Milli-Q Element, Millipore, MA) and measured on ICP-MS (Agrilent 7500ce; Agilent Technologies). HvIRT1 and HvZIP5 dependent transport activity were calculated by subtracting empty vector pFL6.1 mediated uptake rates from the corresponding HvIRT1 and HvZIP5 values, respectively. Each point represents the mean of triplicate measurements and error bars represent ± SE.