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Utilize este identificador para citar ou criar um link para este item: http://acervodigital.unesp.br/handle/11449/75736
Título: 
Subcellular localization and kinetic characterization of a gill (Na +, K+)-ATPase from the giant freshwater prawn macrobrachium rosenbergii
Autor(es): 
Instituição: 
  • Universidade de São Paulo (USP)
  • Universidade Federal da Paraíba (UFPB)
  • Universidade Estadual Paulista (UNESP)
ISSN: 
  • 0022-2631
  • 1432-1424
Resumo: 
The stimulation by Mg2+, Na+, K+, NH 4 +, and ATP of (Na+, K+)-ATPase activity in a gill microsomal fraction from the freshwater prawn Macrobrachium rosenbergii was examined. Immunofluorescence labeling revealed that the (Na +, K+)-ATPase α-subunit is distributed predominantly within the intralamellar septum, while Western blotting revealed a single α-subunit isoform of about 108 kDa M r. Under saturating Mg2+, Na+, and K+ concentrations, the enzyme hydrolyzed ATP, obeying cooperative kinetics with V M = 115.0 ± 2.3 U mg-1, K 0.5 = 0.10 ± 0.01 mmol L-1. Stimulation by Na+ (V M = 110.0 ± 3.3 U mg-1, K 0.5 = 1.30 ± 0.03 mmol L -1), Mg2+ (V M = 115.0 ± 4.6 U mg -1, K 0.5 = 0.96 ± 0.03 mmol L-1), NH4 + (V M = 141.0 ± 5.6 U mg -1, K 0.5 = 1.90 ± 0.04 mmol L-1), and K+ (V M = 120.0 ± 2.4 U mg-1, K M = 2.74 ± 0.08 mmol L-1) followed single saturation curves and, except for K+, exhibited site-site interaction kinetics. Ouabain inhibited ATPase activity by around 73 % with K I = 12.4 ± 1.3 mol L-1. Complementary inhibition studies suggest the presence of F0F1-, Na+-, or K +-ATPases, but not V(H+)- or Ca2+-ATPases, in the gill microsomal preparation. K+ and NH4 + synergistically stimulated enzyme activity (≈25 %), suggesting that these ions bind to different sites on the molecule. We propose a mechanism for the stimulation by both NH4 +, and K+ of the gill enzyme. © 2013 Springer Science+Business Media New York.
Data de publicação: 
1-Jul-2013
Citação: 
Journal of Membrane Biology, v. 246, n. 7, p. 529-543, 2013.
Duração: 
529-543
Palavras-chaves: 
  • (Na+, K+)-ATPase
  • Ammonium/potassium stimulation
  • ATP
  • Giant freshwater prawn
  • Gill microsome
  • Macrobrachium rosenbergii
  • adenosine triphosphatase (calcium)
  • adenosine triphosphatase (potassium sodium)
  • adenosine triphosphatase (potassium)
  • adenosine triphosphate
  • ammonia
  • magnesium ion
  • ouabain
  • potassium ion
  • proton transporting adenosine triphosphatase
  • proton transporting adenosine triphosphate synthase
  • sodium ion
  • alpha chain
  • cellular distribution
  • controlled study
  • enzyme activity
  • enzyme inhibition
  • enzyme kinetics
  • gill
  • hemolymph
  • hydrolysis
  • immunofluorescence
  • immunolocalization
  • microsome
  • nonhuman
  • Western blotting
  • Strophanthus gratus
Fonte: 
http://dx.doi.org/10.1007/s00232-013-9565-4
Endereço permanente: 
Direitos de acesso: 
Acesso restrito
Tipo: 
outro
Fonte completa:
http://repositorio.unesp.br/handle/11449/75736
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