AMINO-ACID DEPRIVATION LEADS TO THE EMERGENCE OF SYSTEM-A ACTIVITY AND THE SYNTHESIS OF A SPECIFIC MEMBRANE GLYCOPROTEIN IN THE BOVINE RENAL EPITHELIAL-CELL LINE NBL-1

1. Amino acid deprivation of confluent monolayers of the bovine renal epithelial cell line NBL-1 causes a stimulation of Na+-dependent alanine transport. 2. This stimulation is mediated by a protein-synthesis-dependent induction of 2-(methylamino)isobutyric acid (methyl-AIB)-sensitive alanine transport activity (System A), which was not previously present in these cells. 3. Induction was prevented by the addition of methyl-AIB, alanine or glutamine. 4. Tunicamycin prevented the induction of alanine transport activity. 5. Induction of System A activity was accompanied by incorporation of [H-3]mannose into a single membrane protein band of molecular mass 113-140 kDa. 6. These results are consistent with the possibility that induced System A activity in confluent NBL-1 cells is mediated by the synthesis of a 113-140 kDa membrane glycoprotein.