phenylalanylalanine and kyotorphin

We have studied functional properties of peptide transport in the pheochromocytoma neuroendocrine cell line from rat. The neutral peptide D-Phe-L-Ala (resistant to hydrolysis) is a good substrate for uptake into these cells. Transport is substantially inhibited by diethylpyrocarbonate pretreatment and is stimulated by external acidification. It is sodium-independent and, unexpectedly, insensitive to membrane potential. Peptide uptake is inhibited by a wide variety of other di- and tripeptides but not by amino acids. The neuropeptide kyotorphin (opioid dipeptide (L-Tyr-L-Arg)) inhibits uptake of labelled peptide and trans-stimulates efflux showing that it is a transported substrate. These findings are discussed in relation to the molecular basis and physiological role of this transport system.

Topics: Animals; Anti-Bacterial Agents; Carrier Proteins; Diethyl Pyrocarbonate; Dipeptides; Endorphins; Hydrogen-Ion Concentration; Membrane Potentials; Neurosecretory Systems; Oligopeptides; PC12 Cells; Peptide Transporter 1; Protein Transport; Rats; Reverse Transcriptase Polymerase Chain Reaction; Symporters