Methylmercury is a potent inhibitor of membrane adenyl cyclase

THE toxicity of methylmercury has taken on added importance since it was discovered that inorganic mercury can be converted to methylmercury by bacteria in bottom sediments of lakes and homogenates of rotting fish 1,2 . The mechanism for methylation of inorganic mercury by bacteria has been described in some detail 3,4 . Although there have been several documented incidents involving the toxicity of alkylmercury derivates 5–7 , the basis for methylmercury toxicity has not been defined unambiguously. One possible target site for methylmercury—the plasma membrane—is described in this communication.