Inhibition of nitrate transport by anti-nitrate reductase IgG fragments and the identification of plasma membrane associated nitrate reductase in roots of barley seedlings

• Published in: Plant physiology (Bethesda) Vol. 88; no. 4; pp. 1141 - 1145
• Main Authors: Ward, M.R, Tischner, R, Huffaker, R.C
• Format: Journal Article
• Language: English
• Published: Ames Research Center American Society of Plant Physiologists 01-12-1988
• Subjects: Adenosine triphosphatases; Antiserum; Barley; Biological and medical sciences; Biological Transport - drug effects; Biological Transport - physiology; Cell Fractionation; Cell Membrane - enzymology; Cell Membrane - metabolism; Cell membranes; CELL STRUCTURE; Chlorella - immunology; Enzymes; ESTRUCTURA CELULAR; Fundamental and applied biological sciences. Psychology; Hordeum - enzymology; Hordeum - metabolism; HORDEUM VULGARE; Immune Sera - immunology; Immune Sera - pharmacology; Immunoglobulin G - immunology; Immunoglobulin G - pharmacology; IMMUNOGLOBULINE; IMMUNOGLOBULINS; INMUNOGLOBULINA; Life Sciences (General); Metabolism; Microsomes; NITRATE; Nitrate Reductases - antagonists & inhibitors; Nitrate Reductases - immunology; Nitrate Reductases - metabolism; NITRATES; Nitrates - metabolism; Nitrates - pharmacokinetics; NITRATOS; Nitrogen metabolism; OXIDOREDUCTASES; OXIDORREDUCTASAS; OXYDOREDUCTASE; Plant physiology and development; Plant roots; Plant Roots - enzymology; Plant Roots - metabolism; Plants; PLANTULAS; PLANTULE; RACINE; RAICES; ROOTS; SEEDLINGS; Space life sciences; STRUCTURE CELLULAIRE; TRANSLOCACION; TRANSLOCATION; Non-Nasa Center; Nasa Discipline Number 61-10; Nasa Discipline Life Support Systems; Nasa Program Celss; Monocotyledones; Immunoglobulins; Hordeum vulgare; Root; Nitrates; Enzymatic activity; Gramineae; Nitrate reductase; Membrane transport; Angiospermae; Plasma membrane; Spermatophyta; Inhibition; NASA Discipline Life Support Systems; NASA Discipline Number 61-10; NASA Program CELSS; Non-NASA Center
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.88.4.1141

Membrane associated nitrate reductase (NR) was detected in plasma membrane (PM) fractions isolated by aqueous two-phase partitioning from barley (Hordeum vulgare L. var CM 72) roots. The PM associated NR was not removed by washing vesicles with 500 millimolar NaCl and 1 millimolar EDTA and represented up to 4% of the total root NR activity. PM associated NR was stimulated up to 20-fold by Triton X-100 whereas soluble NR was only increased 1.7-fold. The latency was a function of the solubilization of NR from the membrane. NR, solubilized from the PM fraction by Triton X-100 was inactivated by antiserum to Chlorella sorokiniana NR. Anti-NR immunoglobulin G fragments purified from the anti-NR serum inhibited NO3
- uptake by more than 90% but had no effect on $\text{NO}_{2}{}^{-}$ uptake. The inhibitory effect was only partially reversible; uptake recovered to 50% of the control after thorough rinsing of roots. Preimmune serum immunoglobulin G fragments inhibited NO3
- uptake 36% but the effect was completely reversible by rinsing. Intact NR antiserum had no effect on NO3
- uptake. The results present the possibility that NO3
- uptake and NO3
- reduction in the PM of barley roots may be related.