Glucose induces two amino acid transport systems in Chlorella.
In autotrophically grown Chlorella cells, glucose induces a hexose transport system but, at the same time, the synthesis of two amino acid transport systems is also induced. Thus, the rates of uptake of glycine, L-alanine, L-proline, and L-serine, all of which compete with each other for entry into the cells, increase more than 100-fold when the algae are pretreated with glucose. The rates of L-arginine and L-lysine uptake increase by a factor of 25 to 50. The accumulation of proline and arginine within the cells amounts to 200- and 600-fold, respectively. Glucose does not cause the positive effect on amino acid uptake by serving as metabolic substrate because the nonmetabolizable 6-deoxyglucose also acts as inducer. Cycloheximide prevents the induction. The induced transport system for the four neutral amino acids has a turnover with a half-life of 7 hr, which corresponds closely to the half-life of the hexose transport system. The transport system for the basic amino acids, on the other hand, disappears with a half-life of 25 hr.
D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism; D000460:Chlorophyta / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D011392:Proline / Q000378:metabolism
D000596:Amino Acids; D002352:Carrier Proteins; D001120:Arginine; D011392:Proline; D005947:Glucose; D000409:Alanine