ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Changes in amino acid transport activity by system A (a Na+-dependent agency with affinity for a discrete group of neutral amino acids) caused by the addition of serum to serum-deprived cultured chick embryo fibroblasts have been evaluated by measurements of 14C-labeled L-proline and α-methylaminoisobutyric acid uptake under conditions approaching initial entry rates. Dialysed serum was as effective as undialysed serum in stimulating amino acid transport. This effect was inhibited by 7 μM cycloheximide, by 80 nM actinomycin D and by 40 μM cordycepin, but not by 0.3 mM cytosine arabinoside. Cultured avian fibroblasts previously incubated in a cycloheximide-containing medium (phase of inhibited translation) in the presence of serum, subsequently exhibited a net increase of proline transport activity when transferred to a medium containing actinomycin D (phase of inhibited transcription). Omission of serum in the cycloheximide-phase prevented the increase of transport activity during subsequent incubation in the actinomycin D-phase; omission of serum in the actinomycin D-phase allowed a shorter and less pronounced increase of transport activity than in the presence of serum. Additions of actinomycin D or cycloheximide slightly increased the rate of decay of amino acid transport caused by serum withdrawal. These observations suggest that in cultured avian fibroblasts, serum modulates the activity of transport system A by a mechanism acting at the transcription level.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1040980207
