Elucidation of an a and L system for amino acid transport in the human lymphoblast using a membrane filtration technique |
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Authors: | Richard Bass Ellis Englesberg |
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Institution: | (1) Section in Biochemistry and Molecular Biology, Department of Biological Sciences, University of California, Santa Barbara, 93106 Santa Barbara, California |
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Abstract: | Summary Optimum conditions have been established for the measurement of amino acid transport by human lymphoblastoid cell lines using
a membrane-filtration technique. The parameters we found to be important for the reproducibility of the method are: the types
and combination of filters, the strength of the vacuum applied to the filters and the density of the cultures at the time
of harvesting and during uptake and filtration. We found that bovine serum albumin added to phosphate buffered saline (PBS)
glucose in which the cells are washed, resuspended and assayed is essential for the maintenance of viability, the prevention
of clumping and the retention of the accumulated amino acid. Using this procedure we have characterized two transport systems
for the neutral amino acids; an A and an L system, which are similar but not identical to the A and L systems characterized
in rodent cell lines. These A and L systems have characteristically lower Km's and Vm's for alanine and phenylalanine, when
compared to rodent cell lines. In addition, we find α-AIB to be a poor competitor of alanine and phenylalanine uptake.
This work was supported by Grant No. CA18644, awarded by the National Cancer Institute, Department of Health, Education and
Welfare, and from a grant from the National Science Foundation under Grant No. PCM 76-24328. |
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Keywords: | human lymphoblast amino acid transport membrane filtration alanine phenylalanine bovine serum albumin alpha-aminoisobutyric acid |
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