National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Transcriptional regulation of PIN4 protein, membrane transporter of plant hormone auxin.
Hurný, Andrej ; Petrášek, Jan (advisor) ; Holá, Dana (referee)
PIN-FORMED (PIN) proteins are plant-specific secondary transporters acting in the efflux of plant signaling molecule auxin from cells. Their asymmetrical localization within cells determines the directionality of auxin flow and thereby influences plant development. The activity of PIN proteins is regulated at multiple levels; however the primary step in the regulation of PIN proteins takes place at the level of gene transcription. Therefore the main focus of this diploma thesis is the characterization of the transcriptional regulation of PIN proteins, namely PIN4 protein. The observation of plants carrying transcriptional fusion consisting of various lengths of PIN4 promoter and green fluorescent protein (GFP) showed which part of PIN4 promoter is essential for binding transcription factors and for the start of transcription. This part of PIN4 promoter was used as bait for transcription factors in yeast one hybrid screens. Altogether, 24 transcription factors were identified in which the most numerous were transcription factors from GATA and APETALA2 (AP2)/ETHYLENE RESPONSE FACTOR (ERF) families. To verify the interactions between identified transcription factors and PIN4 promoter, the protoplast transient expression assay was used. Protoplasts isolated from Arabidopsis thaliana leaves and tobacco BY-2 cell...
The role of AGC protein kinases in the regulation of auxin transport
Martincová, Marie ; Petrášek, Jan (advisor) ; Opatrný, Zdeněk (referee)
There are several members of the subfamily of plant AGC kinases (AGCVIII) suggested to play a role in the regulation of auxin transport, protein kinases PID, WAG1, WAG2 and D6. They all have been shown to perform regulatory phosphorylation of PIN auxin efflux carriers. It is the asymmetrical subcellular localization of PIN proteins that enables the auxin molecules to be transported through a tissue in a polar manner. Regulation of their expression, localization or activity can therefore affect the quantity and directionality of auxin transport. This thesis is focused on better understanding of the PID-mediated regulation of auxin transport. The auxin accumulation as well as the localization of PIN and PID proteins has been studied using stable and transient expression of Arabidopsis thaliana PID in tobacco cell line BY-2. As shown here, the activity of PID does not enhance the activity of PINs, but still it has a positive effect on auxin efflux by increasing the amount of PIN proteins on the plasma membrane. Results presented here suggest that PID-mediated phosphorylation of PIN proteins most likely promotes their exocytosis from endosomal compartments towards the plasma membrane. Using transient co-expression of PID kinase mutated in its ATP-binding site and PIN1-RFP it was shown that functional...

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