DEVELOPMENTAL AND OTHER ASPECTS OF [35S]CYSTEINE TRANSPORT BY RAT BRAIN SYNAPTOSOMES |
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| Authors: | Shing-Mei Hwang Stanton Segal |
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| Institution: | Division of Biochemical Development and Molecular Diseases, Children's Hospital of Philadelphia, and Departments of Pediatrics and Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, U.S.A. |
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| Abstract: | Abstract— Cysteine uptake by rat brain synaptosomes occurs by active transport. The uptake by synaptosomes isolated from newborn brain is slower and the concentration gradient achieved is lower than that observed in adult tissue. Synaptosomal fractions from both adult and newborn rat brains accumulate cysteine by two saturable systems. The calculated parameters show that the maximum rates of cysteine uptake in adult synaptosomes are approximately twice that observed in newborn synaptosomes for both the high and low affinity systems. The uptake by the high affinity system is sodium dependent and is inhibited by glycine and dibasic amino acids. Uptake by synaptosomes from 14-day-old animals is close to that observed in adult tissue. The uptake of cysteine differs greatly from that of cystine since the oxidized form, cystine, is taken up more slowly by systems with low affinities which are sodium independent, do not interact with dibasic amino acids and are independent of age. |
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