IDENTIFICATION AND PARTIAL CHARACTERIZATION OF A NOVEL MEMBRANE GLYCOPROTEIN INDUCED BY AMINO-ACID DEPRIVATION IN RENAL EPITHELIAL-CELLS

We have identified a protein of 110 kDa in the renal epithelial cell l ine NBL-1, which is induced on incubation of the cells in an amino-aci d-free medium. The protein was purified on conA-Sepharose and subjecte d to N-terminal sequencing. The sequence obtained, VDRINFKT, does not correspond to any protein in the databases. Antipeptide antibodies mad e to this sequence recognised a single protein of 110 kDa in whole cel l membranes and in a conconavalin A. protein extract. Using the antibo dy on Western blots, the protein was induced 2.5-3 fold in 10-15 h and the induction was inhibited by cycloheximide and tunicamycin. The pro tein was found also in rat liver plasma membranes. A procedure for the partial purification of this protein from rat liver is described, and some internal sequence is reported. The possible relationship of the induction of this novel protein to the induction of amino acid transpo rt in these cells by amino acid deprivation is discussed.