Looks like the GR protein normally acts upstream of ethylene signaling (perhaps as an inhibitor of a gene critical in the Ethylene production pathway(s) early in fruit development)
Could normally act as a natural "inhibitor" that is normally removed or interfered with during ripening, so it might be that over-expression of the protein also stops the normal removal or interference mechanism (the study says that in the mutant a protein that is overexpressed suppresses ethylene pathways AND overexpression of the same protein in an experimental transgenic plant causes the same effect)
The paper was published in 2006.. wonder if they know more about mechanism now?
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