A re-examination of the Na+-independent binding of [3H]beta-alanine to rat brain stem-spinal cord.
The Na+-independent binding of [3H]beta-alanine to rat brain stem plus spinal cord was reinvestigated, in order to study in more detail the characteristics of previously described beta-alanine binding processes. Binding was absent when amino acid-free postnuclear supernatants or crude synaptic membranes were used. Experiments performed with several other Na+-free preparations showed a sole binding component, irrespective of the preparation used. Biochemical characterization of this Na+-independent binding, using frozen/thawed/washed synaptosomal-mitochondrial fractions, showed that binding reached a plateau between 7 min and 13 min, increasing thereafter. Binding was linear with fraction protein over a range of 200-415 micrograms/ml incubation medium. Binding was completely inhibited by glycine, alanine, alpha-aminobutyric acid, beta-aminoisobutyric acid, hypotaurine and strychnine, and to a lesser extent by 2,2-dimethyl-beta-alanine, brucine and gelsemine. It was insensitive to taurine, gamma-aminobutyric acid (GABA), 2-guanidinoethanesulfonic acid (GES), carnosine, and bicuculline methiodide. Binding was reversible, saturable (KD 20 microM), and heat sensitive.
Orensanz
L M
LM
Departamento de Investigación, Hospital Ramón y Cajal, Madrid, Spain.
Ambrosio
E
E
Fernández
I
I
Montero
M T
MT
D000409:Alanine / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D001933:Brain Stem / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000502:physiology*; D013116:Spinal Cord / Q000378:metabolism*; D013331:Strychnine / Q000378:metabolism; D015091:beta-Alanine / Q000378:metabolism*
D000596:Amino Acids; D015091:beta-Alanine; D012964:Sodium; D013331:Strychnine; D000409:Alanine