01854naa a2200181 a 450000100080000000500110000800800410001910000190006024501090007926000090018852013430019765000140154070000190155470000200157370000150159370000220160877300420163015287342025-07-07       1982    bl uuuu     u00u1 u    #d1 aCORBETT, A. D.  aDynorphin 1-8 and dynorphin 1-9 are ligands for the k-subtype of opiate receptor.h[electronic resource]  c1982  aAbstract: It is generally accepted that there are three subtypes of opiate receptor: µ, δ and κ. The main endogenous ligands for the µ-and δ-sites are Met5-enkephalin, Leu5-enkephalin and β-endorphin, whereas the putative endogenous ligands for the κ-binding site were unknown until recent observations suggested that dynorphin1–13 might be a candidate. The most convincing evidence for this view has been presented by Goldstein and his colleagues who showed that dynorphin1–13 is a specific endogenous ligand for the κ-receptor and has a high potency and long duration of action1–13. We show here that the sequences Leu5-enkephalyl-Arg-Arg-Ile (dynorphin1–8) and, particularly, Leu5-enkephalyl-Arg-Arg-Ile-Arg (dynorphin1–9) are selective ligands for the κ-binding site. Whereas dynorphin1–13 and dynorphin1–17 are relatively resistant to the action of peptidase and have a long duration of action in vitro after wash-out, dynorphin1–8 and dynorphin1–9 are readily degraded by peptidases and their duration of action is much shorter. For this and other reasons, the possibility will have to be considered that dynorphin1–8 or dynorphin1–9 may be transmitters or modulators at the κ-binding site while dynorphin1–13 and dynorphin1–17 may act hormonally, that is, at a distance from the site of release.  aReceptors1 aPATERSON, S J.1 aMcKNIGHT, A. T.1 aMAGNAN, J.1 aKOSTERLITZ, H. W.  tNaturegv. 299, p. 79-80, Sept. 1982.