Open AccessInfluence of Calf Serum on the Transport of 2‐Aminoisobutyric Acid in Embryonic Rat Fibroblasts
Author(s) -
FRANK Werner,
RISTOW HansJürgen
Publication year - 1974
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1974.tb03837.x
Subject(s) - ouabain , aminoisobutyric acid , amino acid , efflux , stimulation , embryonic stem cell , potassium , biochemistry , chemistry , cell culture , alanine , biology , medicine , endocrinology , sodium , gene , genetics , organic chemistry
Transport of 2‐aminoisobutyric acid in embryonic rat fibroblasts is mediated by a carrier system, K m, app. = 8 × 10 −3 M. It was also shown by competition experiments with naturally occurring amino acids that the alanine carrier is responsible for 2‐aminoisobutyric transportation. With cells incubated for 24 h in serum‐free medium, a final K m, app. cannot be demonstrated indicating that under these conditions uptake occurs only by diffusion. After stimulation of the cells by the growth‐stimulating serum factors S1 and S2 no increase in accumulation of 2‐aminoisobutyric acid was found during the first hour, but a K m, app. value can be measured after about 2 h. Efflux of 2‐aminoisobutyric acid is also brought about by an active mechanism which is strongly dependent on the temperature and potassium concentration of the culture medium, and which is also influenced by ouabain. In the permanently growing transformed rat cell lines which have been examined, transport of 2‐aminoisobutyric acid appears to be independent of the presence of serum factors, nearly identical K m, app. values being found within cells grown with and without serum.