Exposure to toxic concentrations of aluminum activates a MAPK-like protein in cell suspension cultures of Coffea arabica.

Addition of a toxic concentration of aluminum (Al) to cell suspension cultures of Coffea arabica L. induced the rapid and transient activation of a protein kinase that phosphorylates myelin basic protein (MBP), as revealed by in-gel kinase assays. This enzyme with an apparent molecular mass of 58 kDa was activated shortly after cells were exposed to 50 microM AlCl(3), a concentration previously shown to produce toxicity in plant cells in vitro.