Although the molecular mechanisms by which plants respond to gibberellins a
re largely unknown, several components of the signal transduction pathway h
ave been identified and a broad outline of how these components act in sign
al transduction is emerging. One component of the pathway, SPINDLY, is beli
eved to be an O-GlcNAc transferase that post-translationally modifies cytos
olic and nuclear proteins by the addition of O-linked N-acetylglucosamine.
Although analysis of the properties of O-GlcNAc-modified proteins from anim
als has led to the hypothesis that this modification is regulatory, it has
not been linked to specific signal transduction pathways.