TY - JOUR
T1 - Uptake of [3H]L-serine in rat brain synaptosomal fractions
AU - Takarada, Takeshi
AU - Balcar, Vladimir J.
AU - Baba, Katsuhiro
AU - Takamoto, Akiko
AU - Acosta, Gabriela B.
AU - Takano, Katsura
AU - Yoneda, Yukio
N1 - Funding Information:
The authors wish to acknowledge Ms. Hiroko Saiki and Ms. Ayame Sano for their excellent technical assistance. VJB wishes to thank to the Japanese Ministry of Education, Science, Sports, Culture and Technology for funding his position at Kanazawa University. GBA was supported by The Japan Society for Promotion of Science (JSPS). This work was supported in part by Grants-in-Aids for Scientific Research to YY and VJB from the Ministry of Education, Science, Sports, Culture and Technology, Japan.
PY - 2003/9/5
Y1 - 2003/9/5
N2 - Accumulation of [3H]L-serine in crude synaptosomal fractions freshly prepared from rat brain has been found to be temperature-sensitive and to consist of both Na+-dependent and Na+-independent components. The accumulation of [3H]L-serine measured at submicromolar concentrations had a distinct substrate selectivity, different from the uptake of [3H]L-proline, [3H]L-glutamate and [3H]GABA. It was fully inhibited by L-glutamine, L-asparagine, L-cysteine, L-alanine, L-leucine, L-isoleucine, L-tyrosine, L-phenylalanine, L-threonine and by the synthetic marker for the large neutral amino acid transport systems 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid, but not influenced by β-alanine, taurine, glycine nor was it inhibited by the marker for the A system, L-2-methylamino isobutyric acid. D-Serine at 1 mM concentration produced no significant inhibition of the accumulation of 10 nM [3H]L-serine. We conclude that L-serine uptake observed in the present study is mediated by at least two distinct transport systems: a Na+-dependent one of lower affinity (Km in mM range) and a Na+-independent system of higher affinity (Km∼20-100 μM). Characteristics of [3H]L-serine accumulation displayed at low substrate concentrations suggest that it was mediated neither by the typical 'A', nor by the 'large neutral', amino acid transport systems but predominantly by transporters belonging to the recently identified LAT (L-amino acid transporter) family.
AB - Accumulation of [3H]L-serine in crude synaptosomal fractions freshly prepared from rat brain has been found to be temperature-sensitive and to consist of both Na+-dependent and Na+-independent components. The accumulation of [3H]L-serine measured at submicromolar concentrations had a distinct substrate selectivity, different from the uptake of [3H]L-proline, [3H]L-glutamate and [3H]GABA. It was fully inhibited by L-glutamine, L-asparagine, L-cysteine, L-alanine, L-leucine, L-isoleucine, L-tyrosine, L-phenylalanine, L-threonine and by the synthetic marker for the large neutral amino acid transport systems 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid, but not influenced by β-alanine, taurine, glycine nor was it inhibited by the marker for the A system, L-2-methylamino isobutyric acid. D-Serine at 1 mM concentration produced no significant inhibition of the accumulation of 10 nM [3H]L-serine. We conclude that L-serine uptake observed in the present study is mediated by at least two distinct transport systems: a Na+-dependent one of lower affinity (Km in mM range) and a Na+-independent system of higher affinity (Km∼20-100 μM). Characteristics of [3H]L-serine accumulation displayed at low substrate concentrations suggest that it was mediated neither by the typical 'A', nor by the 'large neutral', amino acid transport systems but predominantly by transporters belonging to the recently identified LAT (L-amino acid transporter) family.
KW - LAT
KW - Large neutral amino acid
KW - Small neutral amino acid
KW - System A
KW - System L
KW - Transport
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U2 - 10.1016/S0006-8993(03)03024-5
DO - 10.1016/S0006-8993(03)03024-5
M3 - Article
C2 - 12914964
AN - SCOPUS:0043162073
VL - 983
SP - 36
EP - 47
JO - Molecular Brain Research
JF - Molecular Brain Research
SN - 0006-8993
IS - 1-2
ER -