ABC Transporters and Their Function at the Plasma Membrane

Knöller, Anne Sophie; Murphy, Angus S.

doi:10.1007/978-3-642-13431-9_16

Cited by 9 publications

(10 citation statements)

References 109 publications

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“…6e). This uptake effect may be specific to ABCB4 and related ABCB4 isoforms (Knöller and Murphy, 2011), as no IAA uptake could be observed in the ABCB19 auxin efflux transporter under any conditions. Western blot analysis of membrane fractions confirmed that ABCB4 and ABCB19 proteins were expressed (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Alternatively, ABCB4 transport of a substrate other than auxins or substrate‐independent conformational change associated with the first of two ATP hydrolysis steps required for ABC transport function (Knöller and Murphy, 2011) may expose empty IAA binding sites to IAA within the plasma membrane and result in a net import activity when the ‘open’ conformation of the protein is restored (Aller et al. , 2009).…”

Section: Discussionmentioning

confidence: 99%

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The Arabidopsis concentration‐dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis

et al. 2011

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for BY-2 materials) † These authors contributed equally to this work. SUMMARYArabidopsis ATP-binding cassette B4 (ABCB4) is a root-localised auxin efflux transporter with reported auxin uptake activity in low auxin concentrations. Results reported here demonstrate that ABCB4 is a substrateactivated regulator of cellular auxin levels. The contribution of ABCB4 to shootward auxin movement at the root apex increases with auxin concentration, but in root hair elongation assays ABCB4-mediated uptake is evident at low concentrations as well. Uptake kinetics of ABCB4 heterologously expressed in Schizosaccharomyces pombe differed from the saturation kinetics of AUX1 as uptake converted to efflux at threshold indole-3-acetic acid (IAA) concentrations. The concentration dependence of ABCB4 appears to be a direct effect on transporter activity, as ABCB4 expression and ABCB4 plasma membrane (PM) localisation at the root apex are relatively insensitive to changes in auxin concentration. However, PM localization of ABCB4 decreases with 1-naphthylphthalamic acid (NPA) treatment. Unlike other plant ABCBs studied to date, and consistent with decreased detergent solubility, ABCB4 pro :ABCB4-GFP is partially internalised in all cell types by 0.05% DMSO, but not 0.1% ethanol. In trichoblasts, ABCB4 pro :ABCB4-GFP PM signals are reduced by >200 nM IAA and 2,4-dichlorophenoxyacetic acid (2,4-D). In heterologous systems and in planta, ABCB4 transports benzoic acid with weak affinity, but not the oxidative catabolism products 2-oxindole-3-acetic-acid and 2-oxindole-3-acetyl-b-Dglucose. ABCB4 mediates uptake, but not efflux, of the synthetic auxin 2,4-D in cells lacking AUX1 activity. Results presented here suggest that 2,4-D is a non-competitive inhibitor of IAA transport by ABCB4 and indicate that ABCB4 is a target of 2,4-D herbicidal activity.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Arabidopsis concentration‐dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis

et al. 2011

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“…In plants, the ABC superfamily is divided into eight sub‐families (ABCA–H), and ABC proteins are highly abundant, with more than 120 isoforms in Arabidopsis thaliana and Oryza sativa (rice) alone (Verrier et al ., ). ABC transporters share a common architecture consisting of two transmembrane domains (TMD) housing membrane transit sites and two nucleotide binding/hydrolysis domains (NBD) that provide the energetic basis for substrate movement (Knöller and Murphy, ). The ABCG sub‐class exhibits a TMD–NBD–TMD–NBD architecture, and is divided into plant/fungal‐specific pleiotropic drug resistance (PDR) full‐length transporters and the eukaryotic white brown complex (WBC) half‐size transporters that function as homo‐ or heterodimers to create the TMD–NBD–TMD–NBD structure (Verrier et al ., ).…”

Section: Introductionmentioning

confidence: 99%

ABCG9, ABCG11 and ABCG14 ABC transporters are required for vascular development in Arabidopsis

et al. 2013

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SUMMARYIn order to obtain insights into the regulatory pathways controlling phloem development, we characterized three genes encoding membrane proteins from the G sub-family of ABC transporters (ABCG9, ABCG11 and ABCG14), whose expression in the phloem has been confirmed. Mutations in the genes encoding these dimerizing 'half transporters' are semi-dominant and result in vascular patterning defects in cotyledons and the floral stem. Co-immunoprecipitation and bimolecular fluorescence complementation experiments demonstrated that these proteins dimerize, either by flexible pairing (ABCG11 and ABCG9) or by forming strict heterodimers (ABCG14). In addition, metabolome analyses and measurement of sterol ester contents in the mutants suggested that ABCG9, ABCG11 and ABCG14 are involved in lipid/sterol homeostasis regulation. Our results show that these three ABCG genes are required for proper vascular development in Arabidopsis thaliana.

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“…Generally, ABC four domains display a forward domain architecture (TMD‐NBD) 2 (Figure A; Crouzet et al ), whereas PDR domains remain in a reverse orientation to form (NBD‐TMD) 2 (Figure B; Rea ; Zhang et al ). Whichever the domain organization, the basic transport function of ABC transporters depends on ATP hydrolysis within the NBDs that ensures the energy to pump substrates across the membrane against a concentration gradient (Oldham et al ; Knöller and Murphy ).…”

Section: Transport Mechanismmentioning

confidence: 99%

Plant Pleiotropic Drug Resistance Transporters: Transport Mechanism, Gene Expression, and Function

Nuruzzaman

Zhang

Cao

et al. 2014

JIPB

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Pleiotropic drug resistance (PDR) transporters belonging to the ABCG subfamily of ATP-binding cassette (ABC) transporters are identified only in fungi and plants. Members of this family are expressed in plants in response to various biotic and abiotic stresses and transport a diverse array of molecules across membranes. Although their detailed transport mechanism is largely unknown, they play important roles in detoxification processes, preventing water loss, transport of phytohormones, and secondary metabolites. This review provides insights into transport mechanisms of plant PDR transporters, their expression profiles, and multitude functions in plants.

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ABC Transporters and Their Function at the Plasma Membrane

Cited by 9 publications

References 109 publications

The Arabidopsis concentration‐dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis

The Arabidopsis concentration‐dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis

ABCG9, ABCG11 and ABCG14 ABC transporters are required for vascular development in Arabidopsis

Plant Pleiotropic Drug Resistance Transporters: Transport Mechanism, Gene Expression, and Function

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