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Titolo:
PURIFIED VESICLES OF TOBACCO CELL VACUOLAR AND PLASMA-MEMBRANES EXHIBIT DRAMATICALLY DIFFERENT WATER PERMEABILITY AND WATER CHANNEL ACTIVITY
Autore:
MAUREL C; TACNET F; GUCLU J; GUERN J; RIPOCHE P;
Indirizzi:
CNRS,INST SCI VEGETALES,BATIMENT 22 F-91198 GIF SUR YVETTE FRANCE CEA SACLAY F-91191 GIF SUR YVETTE FRANCE
Titolo Testata:
Proceedings of the National Academy of Sciences of the United Statesof America
fascicolo: 13, volume: 94, anno: 1997,
pagine: 7103 - 7108
SICI:
0027-8424(1997)94:13<7103:PVOTCV>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
TURGOR PRESSURE RELAXATION; PLANT-CELLS; COMPARTMENT ANALYSIS; LIPID-COMPOSITION; XENOPUS-OOCYTES; PROTEIN; TONOPLAST; FLOW; TIP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
C. Maurel et al., "PURIFIED VESICLES OF TOBACCO CELL VACUOLAR AND PLASMA-MEMBRANES EXHIBIT DRAMATICALLY DIFFERENT WATER PERMEABILITY AND WATER CHANNEL ACTIVITY", Proceedings of the National Academy of Sciences of the United Statesof America, 94(13), 1997, pp. 7103-7108

Abstract

The vacuolar membrane or tonoplast (TP) and the plasma membrane (PM) of tobacco suspension cells were purified by free-flow electrophoresis(FFE) and aqueous two-phase partitioning, with enrichment factors from a crude microsomal fraction of greater than or equal to 4- to 5-foldand reduced contamination by other cellular membranes, For each purified fraction, the mean apparent diameter of membrane vesicles was determined by freeze-fracture electron microscopy, and the osmotic shrinking kinetics of the vesicles were characterized by stopped-flow light scattering. Osmotic water permeability coefficients (P-f) of 6.1 +/- 0.2 and 7.6 +/- 0.9 mu m.s(-1) were deduced for PM-enriched vesicles purified by FFE and phase partitioning, respectively, The associated activation energies (E-a; 13.7 +/- 1.0 and 13.4 +/- 1.4 kcal.mol(-1), respectively) suggest that water transport in the purified PM occurs mostly by diffusion across the lipid matrix, In contrast, water transport in TP vesicles purified by FFE was characterized by (i) a 100-fold higher P-f of 690 +/- 35 mu m.s(-1), (ii) a reduced E-a of 2.5 +/- 1.3 kcal.mol(-1), and (iii) a reversible inhibition by mercuric chloride, up to 83% at 1 mM, These results provide functional evidence for channel-mediated water transport in the TP, and more generally in a higher plant membrane. A high TP P-f suggests a role for the vacuole in buffering osmotic fluctuations occurring in the cytoplasm, Thus, the differential water permeabilities and water channel activities observed in the tobacco TP and PM point to an original osmoregulatory function for water channels in relation to the typical compartmentation of plant cells.

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Documento generato il 25/01/20 alle ore 19:26:17