Internalization of [3H]substance P analogues in NK-1 receptor transfected CHO cells.
The internalization of [3H]propionyl[Met(O2)11]SP(7-11) which binds one binding site and of [3H][Pro9]SP which binds the two binding sites associated with the NK-1 receptor has been examined in CHO cells. The quantity of [3H][Pro9]SP measured inside the cytoplasm in kinetic experiments is fully temperature-dependent. In contrast, [3H]propionyl[Met(O2)11]SP(7-11) internalization reaches the same extent whatever the temperature, although the rate slowed down with lower temperature. The extent of internalization of [3H][Pro(9)]SP relative to the total specific bound is biphasic, when the extent of internalization of [3H]propionyl[Met(O2)11]SP(7-11) remains constant. For [3H][Pro9]SP, a high-affinity high-yield component inhibited in the presence of propionyl[Met(O2)11]SP(7-11) and a low-affinity low-yield component in the internalization process could be determined. Saturation studies show that [3H][Pro9]SP-binding parameters are insensitive to both phenylarsine oxide and monensin treatment, whereas [3H]propionyl[Met(O2)11]SP(7-11) maximal binding is decreased in both cases. Altogether, these data suggest that the two radiolabeled peptides should not follow the same internalization pathway.
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Unité Mixte de Recherches CNRS 7613, Chimie Organique Biologique, Université Pierre & Marie Curie, Aile 44-45, Bo $$;ite courrier 182, 4 place Jussieu, Paris cedex 05, 75252, France. sagan@ccr.jussieu.fr
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D000818:Animals; D001152:Arsenicals / Q000494:pharmacology; D016466:CHO Cells; D006224:Cricetinae; D004705:Endocytosis / Q000187:drug effects; D007700:Kinetics; D008954:Models, Biological; D008985:Monensin / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism*; D018040:Receptors, Neurokinin-1 / Q000235:genetics / Q000378:metabolism*; D013373:Substance P / Q000031:analogs & derivatives* / Q000378:metabolism*; D013696:Temperature; D014162:Transfection
D001152:Arsenicals; D010446:Peptide Fragments; D018040:Receptors, Neurokinin-1; C107105:propionyl-(Met(O2)11)substance P(7-11); C029341:oxophenylarsine; C067285:substance P, Pro(9)-; D013373:Substance P; D008985:Monensin