title: Denervation alters protein-lipid interactions in membrane fractions from electrocytes of Electrophorus electricus (L.).
abstract: Protein-lipid interactions are studied in normal and denervated electrocytes from Electrophorus electricus (L.). Structural modifications of the lipid micro-environment encircling integral membrane proteins in membrane fractions presenting Na(+),K(+)-ATPase activity are investigated using ESR spectroscopy of stearic acid spin labeled at the 14th carbon (14-SASL). The microsomal fraction derived from the innervated electric organ exhibits, on a discontinuous sucrose gradient, a bimodal distribution of the Na(+),K(+)-ATPase activity, bands a and b. Band b is almost absent in microsomes from the denervated organ, and band a', with the same density as band a has lower Na(+),K(+)-ATPase activity. Band a' presents a larger ratio of protein-interacting lipids than band a. Analysis of the lipid stoichiometry at the protein interface indicates that denervation causes at least a twofold average decrease on protein oligomerization. Physical inactivity and denervation have similar effects on protein-lipid interactions. Denervation also influences the selectivity of proteins for fatty acids. Experiments in decreasing pH conditions performed to verify the influence of stearic acid negative charge on protein interaction revealed that denervation produces loss of charge selectivity. The observed modifications on molecular interactions induced by denervation may have importance to explain modulation of enzyme activity.
authors.affiliation: Laboratório de Físico-Química Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Rio de Janeiro 21949-900, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Barriviera
authors.forename: S R
authors.initials: SR
authors.lastname: Louro
authors.forename: E
authors.initials: E
authors.lastname: Wajnberg
authors.forename: A
authors.initials: A
authors.lastname: Hasson-Voloch
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D004593:Electrophorus; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D008055:Lipids; D008565:Membrane Proteins; D000254:Sodium-Potassium-Exchanging ATPase