PIN proteins perform a rate-limiting function in cellular auxin efflux

Petrášek J., Mravec J., Bouchard R., Blakeslee J.J., Abas M., Seifertová D., Wisniewska J., Tadele Z., Kubeš M., Čovanová M., Dhonukshe P., Skůpa P., Benková E., Perry L., Křeček P., Lee O.R., Fink G.R., Geisler M., Murphy A.S., Luschnig C., Zažímalová E., Friml J.
SCIENCE 312: 914-918, 2006

Keywords: auxin transport; PIN proteins; PGP transporters; MDR
Abstract: Intercellular flow of the phytohormone auxin underpins multiple developmental processes in plants. Plant-specific pin-formed (PIN) proteins and several phosphoglycoprotein (PGP) transporters are crucial factors in auxin transport–related development, yet the molecular function of PINs remains unknown. Here, we show that PINs mediate auxin efflux from mammalian and yeast cells without needing additional plant-specific factors. Conditional gain-of-function alleles and quantitative measurements of auxin accumulation in Arabidopsis and tobacco cultured cells revealed that the action of PINs in auxin efflux is distinct from PGP, rate-limiting, specific to auxins, and sensitive to auxin transport inhibitors. This suggests a direct involvement of PINs in catalyzing cellular auxin efflux.
DOI: IEB authors: Milada Čovanová, Jan Petrášek, Petr Skůpa, Eva Zažímalová