PGP4, an ATP Binding Cassette P-Glycoprotein, Catalyzes Auxin Transport in Arabidopsis thaliana Roots

• Published in: The Plant cell Vol. 17; no. 11; pp. 2922 - 2939
• Main Authors: Terasaka, Kazuyoshi, Blakeslee, Joshua J, Titapiwatanakun, Boosaree, Peer, Wendy A, Bandyopadhyay, Anindita, Makam, Srinivas N, Lee, Ok Ran, Richards, Elizabeth L, Murphy, Angus S, Sato, Fumihiko, Yazaki, Kazufumi
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01-11-2005
• Subjects: ABC transporters; Acetic acid; Animals; Antiserum; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - isolation & purification; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; ATP; ATP Binding Cassette Transporter, Sub-Family B - genetics; ATP Binding Cassette Transporter, Sub-Family B - isolation & purification; ATP Binding Cassette Transporter, Sub-Family B - metabolism; ATP binding cassette transporters; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - isolation & purification; ATP-Binding Cassette Transporters - metabolism; Auxins; Cell Membrane - metabolism; Cell Polarity - physiology; cytochemistry; Detoxification; epidermis (plant); gene expression; Gene Expression Regulation, Plant - physiology; Genes, Reporter - physiology; HeLa Cells; Humans; Indoleacetic Acids - metabolism; Insulin antibodies; messenger RNA; Mutation - physiology; Phenotype; Phenotypes; physiological transport; Plant cells; Plant Epidermis - metabolism; Plant roots; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Plant Shoots - growth & development; Plant Shoots - metabolism; Plants; plasma membrane; Rabbits; RNA; root tips; Roots; Seedlings; translocation (plant physiology)
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.105.035816

Members of the ABC (for ATP binding cassette) superfamily of integral membrane transporters function in cellular detoxification, cell-to-cell signaling, and channel regulation. More recently, members of the multidrug resistance P-glycoprotein (MDR/PGP) subfamily of ABC transporters have been shown to function in the transport of the phytohormone auxin in both monocots and dicots. Here, we report that the Arabidopsis thaliana MDR/PGP PGP4 functions in the basipetal redirection of auxin from the root tip. Reporter gene studies showed that PGP4 was strongly expressed in root cap and epidermal cells. PGP4 exhibits apolar plasma membrane localization in the root cap and polar localization in tissues above. Root gravitropic bending and elongation as well as lateral root formation were reduced in pgp4 mutants compared with the wild type. pgp4 exhibited reduced basipetal auxin transport in roots and a small decrease in shoot-to-root transport consistent with a partial loss of the redirective auxin sink in the root. Seedlings overexpressing PGP4 exhibited increased shoot-to-root auxin transport. Heterologous expression of PGP4 in mammalian cells resulted in 1-N-naphthylthalamic acid-reversible net uptake of [³H]indole-3-acetic acid. These results indicate that PGP4 functions primarily in the uptake of redirected or newly synthesized auxin in epidermal root cells.