5 prime -Azido-(3,6- sup 3 H sub 2 )-1-naphthylphthalamic acid, a photoactivatable probe for naphthylphthalamic acid receptor proteins from higher plants: Identification of a 23-kDa protein from maize coleoptile plasma membranes

Journal Article · Wed Jan 15 04:00:00 EST 1992 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.89.2.480· OSTI ID:5617966

Zettl, R; Feldwisch, J; Schell, J; Palme, K ^[1]; Boland, W ^[2]

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1. Max-Planck-Inst. fuer Zuechtungsforschung, Koeln (West Germany)
2. Univ. Karlsruhe (West Germany)

1-Naphthylphthalamic acid (NPA) is a specific inhibitor of polar auxin transport that blocks carrier mediated auxin efflux from plant cells. To allow identification of the NPA receptor thought to be part of the auxin efflux carrier, the authors have synthesized a tritiated, photolabile NPA analogue, 5{prime}-azido-(3,6-{sup 3}H{sub 2})NPA (({sup 3}H{sub 2})N{sub 3}NPA). This analogue was used to identify NPA-binding proteins in fractions highly enriched for plasma membrane vesicles isolated from maize coleoptiles (Zea mays L.). Competition studies showed that binding of ({sup 3}H{sub 2})N{sub 3}NPA to maize plasma membrane vesicles was blocked by nonradioactive NPA but not by benzoic acid. After incubation of plasma membrane vesicles with ({sup 3}H{sub 2})N{sub 3}NPA and exposure to UV light, they observed specific photoaffinity labeling of a protein with an apparent molecular mass of 23 kDa. Pretreatment of the plasma membrane vesicles with indole-3-acetic acid or with the auxin-transport inhibitors NPA and 2,3,5-triiodobenzoic acid strongly reduced specific labeling of this protein. This 23-kDa protein was also labeled by addition of 5-azido-(7-{sup 3}H)indole-3-acetic acid to plasma membranes prior to exposure to UV light. The 23-kDa protein was solubilized from plasma membranes by 1% Triton X-100. The possibility that this 23-kDa polypeptide is part of the auxin efflux carrier system is discussed.

• OSTI ID: 5617966
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 89:2; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AUTORADIOGRAPHY
AUXINS
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CEREALS
COLEOPTILE
DICARBOXYLIC ACIDS
ELECTROPHORESIS
ENZYME INHIBITORS
GRAMINEAE
HYDROGEN COMPOUNDS
KINETICS
LILIOPSIDA
MAGNOLIOPHYTA
MAIZE
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHTHALIC ACID
PLANT GROWTH REGULATORS
PLANTS
PROTEINS
REACTION KINETICS
RECEPTORS
TRITIUM COMPOUNDS