Evidence for the plasma membrane localization of Al-activated malate transporter (ALMT1).

Aluminum (Al)-activated malate transporter (ALMT1) was recently identified from wheat (Triticum aestivum). Heterologous expression of ALMT1 led to higher malate exudation that is associated with enhanced Al tolerance in transgenic plants. Here, we show the first direct evidence that ALMT1 is localized in the plasma membrane of Al-tolerant wheat. Phase partitioning experiments showed that this transporter was associated with the plasma membrane fraction. ALMT1 was detected in an Al-tolerant wheat line even without Al treatments. Analysis of transient expression of ALMT1::green fluorescent protein (GFP) in onion and tobacco cells further confirmed this ALMT1 localization.