Table 1

Characterization of neuropeptide Y receptor subtypes

	Y₁	Y₂	Y₄	Y₅	Y₆^1-a
Previous names	—	—	PP1	Y₁-like receptors food intake receptor	Y₅, Y_2B, PP2
Agonist order of potency	NPY (0.2 nM) ≥ PYY (0.7 nM) >> PP (>100 nM)	NPY (0.7 nM) ≈ PYY (0.7 nM) >> PP (>1000 nM)	PP (0.05 nM) > NPY^1-b ≈ PYY^1-b	NPY (0.6 nM) ≥ PYY (1 nM) ≥ PP^1-c	NPY ≈ PYY > PP^1-h
Selective agonists	[Leu³¹,Pro³⁴]NPY^1-e	NPY_13–36 ^1-f	PP	—	—
	[Pro³⁴]NPY^1-e	NPY_3–36 ^1-g
	[Leu³¹,Pro³⁴]PYY^1-e	PYY_13–36 ^1-f
	[Pro³⁴]PYY^1-e	PYY_3–36 ^1-g
Selective antagonists	BIBP 3226	—	—	—	—
	GR23118^1-d
Signal transduction	G_i/o, adenylyl cyclase inhibition	G_i/o, adenylyl cyclase inhibition	G_i,o, adenylyl cyclase inhibition	G_i/o, adenylyl cyclase inhibition	adenylyl cyclase inhibition
Prototypical cell line,	SK-N-MC cells	SMS-KAN cells	?	food intake stimulation?	?
tissue or response	HEL cells	rabbit kidney binding sites

↵1-a No functional protein is expressed in primates due to a truncation in the sixth transmembrane domain.
↵1-b While some investigators have detected low nanomolar affinity others have reported values to be greater than 1 μM, particularly in rats.
↵1-c While rat PP has low affinity at both the rat and human Y₅ receptor (230 nM), human PP as higher affinity in both species (4 nM).
↵1-d Also has high affinity for Y₄ receptors (Gehlert et al., 1996b).
↵1-e Selective relative to Y₂.
↵1-f Selective relative to Y₁ and Y₅.
↵1-g Selective relative to Y₁.
↵1-h Limited available data are controversial; the affinity values in parentheses are median values at mammalian receptors as taken from the various studies referenced in the text.