Developmental control of 2-aminoisobutyric acid transport by 7-and 14-day chick heart cell aggregates. Roles of insulin and amino acids.

摘要: Abstract Cell aggregates cultured from 7-day embryonic avian heart showed a spontaneous increase in A-system 2-aminoisobutyric acid transport when placed protein-free and amino acid-free buffer for 3 hr. The apparent Vmax increased 4.0 to 9.9 nmoles/μl of intracellular fluid volume/10 min l -Proline (5 mM), an transported primarily by the A system, prevented this rise, but -phenylalanine, L-system substrate, had no effect. Actinomycin, puromycin, cycloheximide (55 μM) also time-dependent transport. In contrast, cell 14-day exhibited decrease during 3-hr incubation, 8.3 3.3 min. -Proline, not enhanced percentage proline inhibition was reduced actinomycin or at both ages. Insulin stimulated identical half-maximal concentrations 18 nM 7 14 days development. presence age, insulin prolonged half-life activity twofold. However, days, response 88% [Elsas, L. J., Wheeler, F. B., Danner, D. DeHaan, R. (1975) . J. Biol. Chem. 250, 9381–9390]. basal insulin-stimulated aggregates, neither stimulation. We conclude that inherent developmental control(s), acids, regulated maximal velocity controlling biological turnover protein(s). decreased existing synthesis protein(s) predominant effect shifted posttranslational level synthetic Seven-day spontaneously absence required hormonal stimulation shift balance degradation