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Titolo:
Projection structure of a plant vacuole membrane aquaporin by electron cryo-crystallography
Autore:
Daniels, MJ; Chrispeels, MJ; Yeager, M;
Indirizzi:
Scripps Clin & Res Inst, Dept Cell Biol, La Jolla, CA 92037 USA Scripps Clin & Res Inst La Jolla CA USA 92037 iol, La Jolla, CA 92037 USA Scripps Clin & Res Inst, Div Cardiovasc Dis, La Jolla, CA 92037 USA Scripps Clin & Res Inst La Jolla CA USA 92037 Dis, La Jolla, CA 92037 USA
Titolo Testata:
JOURNAL OF MOLECULAR BIOLOGY
fascicolo: 5, volume: 294, anno: 1999,
pagine: 1337 - 1349
SICI:
0022-2836(199912)294:5<1337:PSOAPV>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
TONOPLAST INTRINSIC PROTEIN; CHIP28 WATER CHANNEL; 3-DIMENSIONAL STRUCTURE; PHASEOLUS-VULGARIS; STORAGE VACUOLES; SEED DEVELOPMENT; PURPLE MEMBRANE; MIP FAMILY; RESOLUTION; MICROSCOPY;
Keywords:
aquaporin; electron cryo-microscopy; image analysis; projection map; tonoplast intrinsic protein;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
65
Recensione:
Indirizzi per estratti:
Indirizzo: Yeager, M Scripps Clin & Res Inst, Dept Cell Biol, 10550 N Torrey Pines Rd, La Jolla, CA 92037 USA Scripps Clin & Res Inst 10550 N Torrey Pines Rd LaJolla CA USA 92037
Citazione:
M.J. Daniels et al., "Projection structure of a plant vacuole membrane aquaporin by electron cryo-crystallography", J MOL BIOL, 294(5), 1999, pp. 1337-1349

Abstract

The water channel protein alpha-TIP is a member of the major intrinsic protein (MIP) membrane channel family. This aquaporin is found abundantly in vacuolar membranes of cotyledons (seed storage organs) and is synthesized during seed maturation. The water channel activity of alpha-TIP can be regulated by phosphorylation, and the protein may function in seed desiccation, cytoplasmic osmoregulation, and/or seed rehydration. alpha-TIP was purified from seed meal of the common bean (Phaseolus vulgaris) by membrane fractionation, solubilization in diheptanoylphosphocholine and anion-exchange chromatography. Upon detergent removal and reconstitution into lipid bilayers, alpha-TIP crystallized as helical tubes. Electron cryo-crystallography of flattened tubes demonstrated that the crystals exhibit plane group p2 symmetry and c222 pseudosymmetry. Since the 2D crystals with p2 symmetry are derived from helical tubes, we infer that the unit of crystallization on the helical lattice is a dimer of tetramers. A projection density map at a resolution of 7.7 Angstrom revealed that alpha-TIP assembles as a 60 Angstrom x 60Angstrom square tetramer. Each subunit is formed by a heart-shaped ring comprised of density peaks which we interpret as alpha-helices. The similarity of this structure to manmalian plasma membrane MIP-family proteins suggests that the molecular design of functionally analogous and genetically homologous aquaporins is maintained between the plant and animal kingdoms. (C) 1999 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 11:41:52