The Beta-Amino Acid Transport System in Friedreich's Ataxia

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Abstract
Taurine and β-amino uptake in cultured skin fibroblasts proceeds through at least two distinct amino acid transport systems. The predominant Bamino acid uptake system which we refer to as the “Beta” system, incorporates taurine in a proportion of 95%, β-alanine in a proportion of 80% and does not incorporate β-amino-isobutyric acid. A second transport system for β-alanine seems to be operative in cultured skin fibroblasts and this system shares the characteristics of system “L” for branched-chain and ringside neutral amino acids. Results of ion depletion experiments, metabolic inhibition by drugs and blocking agents and previous kinetic studies of taurine and β-alanine uptake in cultured skin fibroblasts failed to disclose any major difference in β-amino acid transport between control individuals and patients with Friedreich's ataxia.