A plethora of abiotic and biotic environmental stresses expert their influence on plants via the gaseous hormone ethylene. In addition, aspects of plant development and climactic fruit ripening are regulated by ethylene. Sensitivity to ethylene is presumably mediated by a specific ethylene receptor whose activation signal is then transduced via an unknown cascade pathway. (Raz and Flur, 1993)
Research on the ethylene signal pathway has gained evidence that protein phosphorylation is necessary for ethylene signal transduction. This implicates phosphorylation somewhere in the ethylene signal pathway. Other evidence has suggested the involvment of GTP binding proteins in the ethylene signal transduction. (Berry etal., 1994)
A mutation has given information on the Ethylene receptor (ETR1) protein in Arabidopsis. Mutations in the ETR1 gene confer insensitivity to ethylene. When yeast express this ETR1 Arabidopsis gene they gain ethylene binding capabilities and when the ETR1 gene is truncated the yeast loose ethylene binding capabilities. This suggests the truncated amino-terminal hydrophobic domain of the ETR1 protien is the binding site of ethylene. (Schaller and Bleecker, 1995)
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