Interactions between PGP, PIN, and AUX/LAX Auxin transport proteins from Arabidopsis.
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Journal. Plant Growth Regulation Society of America Quarterly. 34(3).
본문
Abstract
Directional transport of the ,phytohormone ,auxin ,is required for ,the establishment ,and maintenance of plant polar growth. Natural auxins, primarily indole 3-acetic acid (IAA), are ampipathic weak acids that diffuse into membrane bilayers when protonated, suggesting that polar auxin movement is primarily established at the point of cellular efflux. However, recent evidence,indicates that proton-coupled ,uptake transporters also play ,a role ,in polar ,auxin movement, particularly in roots (Swarup et al, 2005). Cellular auxin transport mediated by members of the PGP, PIN, and AUX/LAX protein families has recently been conclusively demonstrated in plant and heterologous expression systems (Chen et al, 1998; Geisler , Blakeslee etal, 2005; Bouchard et al, 2006; Terasaka et al, 2005; Petrasek et al, 2006; Yang et al, 2006). Members,of the ,PIN subfamily of ion-coupled ,major facilitator proteins and P-glycoprotein (PGP) ABC transporters (Sieberer and Leyser, 2006; Geisler and Murphy, 2006) have been shown to independently mediate auxin export, while AUX/LAX proteins and at least one Arabidopsis PGP, PGP4, mediate auxin uptake (Swarup et al, 2005; Yang et al, 2006; Terasaka etal, 2005). In those heterologous expression studies, AUX1 exhibited strict substrate and inhibitor specificities similar to what ,is seen in ,planta. PGPs and PINs did not. Here we characterize PGP interactions with PINs and AUX1 to ascertain whether ,such interactions in plantainfluence rates and specificity of auxin transport. PIN proteins, named for the pinformed inflorescence exhibited by pin1, are plasma membrane
Directional transport of the ,phytohormone ,auxin ,is required for ,the establishment ,and maintenance of plant polar growth. Natural auxins, primarily indole 3-acetic acid (IAA), are ampipathic weak acids that diffuse into membrane bilayers when protonated, suggesting that polar auxin movement is primarily established at the point of cellular efflux. However, recent evidence,indicates that proton-coupled ,uptake transporters also play ,a role ,in polar ,auxin movement, particularly in roots (Swarup et al, 2005). Cellular auxin transport mediated by members of the PGP, PIN, and AUX/LAX protein families has recently been conclusively demonstrated in plant and heterologous expression systems (Chen et al, 1998; Geisler , Blakeslee etal, 2005; Bouchard et al, 2006; Terasaka et al, 2005; Petrasek et al, 2006; Yang et al, 2006). Members,of the ,PIN subfamily of ion-coupled ,major facilitator proteins and P-glycoprotein (PGP) ABC transporters (Sieberer and Leyser, 2006; Geisler and Murphy, 2006) have been shown to independently mediate auxin export, while AUX/LAX proteins and at least one Arabidopsis PGP, PGP4, mediate auxin uptake (Swarup et al, 2005; Yang et al, 2006; Terasaka etal, 2005). In those heterologous expression studies, AUX1 exhibited strict substrate and inhibitor specificities similar to what ,is seen in ,planta. PGPs and PINs did not. Here we characterize PGP interactions with PINs and AUX1 to ascertain whether ,such interactions in plantainfluence rates and specificity of auxin transport. PIN proteins, named for the pinformed inflorescence exhibited by pin1, are plasma membrane