Dynamic control of auxin transport-dependent growth by AGCVIII protein kinases

• D6PKs and PID/WAGs activate PIN auxin efflux carriers.
• D6PKs and PID have differential phosphosite preferences on PINs.
• PID/WAGs also control PIN polarity.
• phot1 phosphorylates ABC transporters and inhibits auxin efflux.
• The subcellular localization of the kinases is dynamically regulated.

Recent years have seen important advances in understanding the Arabidopsis thaliana AGCVIII protein kinases D6 PROTEIN KINASE, PINOID/WAGs, and the phototropins. It has become apparent that these kinases control the distribution of the phytohormone auxin within the plant through phosphorylation of PIN-FORMED efflux carriers or of ABC transporters. Strikingly, D6PK and PID share the same phosphosites in PIN-FORMED proteins but have differential phosphosite preferences, which appear to control the activity and polar distribution of PIN-FORMED transporters. All three AGCVIII kinases are membrane-associated proteins that are dynamically transported to and from the plasma membrane. The implications of this dynamic transport for the activity and cell biological behavior of their phosphorylation substrates are just now starting to be understood.

Figure optionsDownload high-quality image (166 K)Download as PowerPoint slide