Auxin Flashcards
how are phototrophic signals received in a plant?
Phototrophic signals are perceived at the shoot tip and auxin travels down the dark side of the plant
what overall affect does auxin have on the cells it interacts with?
Promotes cell division and expansion below the tip
What is an ARF?
Auxin response factor - transcriptional activator which binds to Aux response elements (Auxres)
What are AUX/IAA?
proteins which bind to ARFs to inhibit transcription of Auxin mediated genes
What part of the ubiquitination pathway does the enzyme E1 mediate?
E1 is thought of as the ubiquitin activating enzyme. Activates Ub by binding it to a cysteine residue (requires ATP)
What part of the ubiquitination pathway does the enzyme E2 mediate?
E2 is the ubiquitin conjugation enzyme. Ubiquitin passed from cysteine residue of E1 to cysteine residue of E2
What part of the ubiquitination pathway does E3 enzyme mediate?
E3 is ubiquitin ligase. Attaches primed ubiquitin to a lysine residue on the cytosolic target protein.
What is an example of a ubiquitin ligase in auxin pathway?
SCF(TIF1)
in total how many ATP molecules are hydrolysed in the ubiquitination of a protein and recognition by the proteasome?
2
How does auxin create a response in a plant cell?
Auxin mediates the degradation of AUX/IAA repressor proteins via the ubiquitin ligase SCF(TIF1).
What type of proteins is TIF1
Is an F box protein and is the receptor for auxin
What role does TIF1/Auxin complex have in the degradation of the target protein?
Auxin binds TIF1 and this complex provides specificity for the target proteins AUX/IAA to select them for ubiquitination and therefore degradation by the proteasome.
What product comes from the degradation of AUX/IAA?
Some of the peptides released in the degradations are ARFS
How is the inhibition pathway of Aux mediated genes restored?
Some of the gene products activated by ARFs are AUX (Aux will be transcribed and inhibition pathway restored)
