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Exogenous Gangliosides GD1b and GD1b‐Lactone, Stably Associated to Rat Brain P 2 Subcellular Fraction, Modulate Differently the Process of Protein Phosphorylation
Author(s) -
Bassi Rosaria,
Chigorao Vanna,
Fiorilli Amelia,
Sonnino Sandro,
Tettamanti Guido
Publication year - 1991
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1991.tb08281.x
Subject(s) - phosphorylation , ganglioside , chemistry , protein phosphorylation , biochemistry , membrane protein , biology , membrane , protein kinase a
GD1b and GD1b‐lactone (GD1b‐L) gangliosides bind to the same extent to a P 2 crude membrane preparation from rat brain. After 30 min of incubation with 10 −4 , 10 5 , and 10 −6 Absolutions of ganglioside, 1,800, 450, and 100 pmol of ganglioside/mg of protein, respectively, were found to be stably associated to the P 2 fraction. This association modifies the phosphorylation process of the P 2 membrane proteins in a dose‐dependent manner, the maximal effect being reached at a ganglioside association of 1.85 nmol/mg of protein and in large part at 450 pmol/mg of protein. The effects of GD1b and GD1b‐L on the phosphorylation of five proteins, showing apparent molecular masses of 17, 20, 36, 41, and 44 kDa, were different after 0.5 min of phosphorylation reaction as well as after 15 min. After 0.5 min of reaction, in the presence of stably associated GD1b, the phosphorylation of the 36‐, 41‐, and 44‐kDa proteins was increased with reference to the control, whereas the phosphorylation of the 17‐ and 20‐kDa proteins was decreased. GD1b‐L exerted qualitatively similar effects only on the 44‐, 41‐, and 36‐kDa proteins and to a strongly reduced degree. After 15 min of reaction, only the phosphorylation of the 36‐kDa protein was stimulated by GD1b; GD1b‐L exerted a similar effect, but to a low degree.