CDB15:0001175 NTS — NTSR2
Experimentally validated in Human, Mixed species; Orthology-inferred in Human, Mouse, Rat, Frog, Zebrafish, Chicken, Macaque, Pig, Dog, Cow, Chimp, Horse, Marmoset, Sheep
Title
Journal:; Year Published:
Abstract
Recycling ability of the mouse and the human neurotensin type 2 receptors depends on a single tyrosine residue.
Journal of cell science, 2002; PubMed, Homo sapiens NTS — Homo sapiens NTSR2
ABSTRACT: Receptor recycling plays a key role in the modulation of cellular responses to extracellular signals. The purpose of this work was to identify residues in G-protein coupled neurotensin receptors that are directly involved in recycling. Both the high affinity receptor-1 (NTR1) and the levocabastine-sensitive NTR2 are internalized after neurotensin binding. Here, we show that only the mouse NTR2 recycled to the plasma membrane, whereas the rat NTR1 and the human NTR2 did not. Using site-directed mutagenesis, we demonstrate that tyrosine 237 in the third intracellular loop is crucial for recycling of the mouse NTR2. We show that the mouse NTR2 is phosphorylated on tyrosine residues by NT. This phosphorylation is essential for receptor recycling since the tyrosine kinase inhibitor genistein blocks this process. The absence of recycling observed with the human NTR2 could be completely explained by the presence of a cysteine instead of a tyrosine in position 237. Indeed, substitution of this cysteine by a tyrosine gave a mutant receptor that has acquired the ability to recycle to the cell surface after neurotensin-induced internalization. This work demonstrates that a single tyrosine residue in the third intracellular loop of a G-protein-coupled receptor is responsible for receptor phosphorylation and represents an essential structural element for receptor recycling.
Neurotensin is an antagonist of the human neurotensin NT2 receptor expressed in Chinese hamster ovary cells.
European journal of pharmacology, 1998; PubMed, Homo sapiens NTS — Homo sapiens NTSR2
ABSTRACT: The human levocabastine-sensitive neurotensin NT2 receptor was cloned from a cortex cDNA library and stably expressed in Chinese hamster ovary (CHO) cells in order to study its binding and signalling characteristics. The receptor binds neurotensin as well as several other ligands already described for neurotensin NT1 receptor. It also binds levocabastine, a histamine H1 receptor antagonist that is not recognised by neurotensin NT1 receptor. Neurotensin binding to recombinant neurotensin NT2 receptor expressed in CHO cells does not elicit a biological response as determined by second messenger measurements. Levocabastine, and the peptides neuromedin N and xenin were also ineffective on neurotensin NT2 receptor activation. Experiments with the neurotensin NT1 receptor antagonists SR48692 and SR142948A, resulted in the unanticipated discovery that both molecules are potent agonists on neurotensin NT2 receptor. Both compounds, following binding to neurotensin NT2 receptor, enhance inositol phosphates (IP) formation with a subsequent [Ca2+]i mobilisation; induce arachidonic acid release; and stimulate mitogen-activated protein kinase (MAPK) activity. Interestingly, these activities are antagonised by neurotensin and levocabastine in a concentration-dependent manner. These activities suggest that the human neurotensin NT2 receptor may be of physiological importance and that a natural agonist for the receptor may exist.