Reference data of H₄R ligands determined in the [³⁵S]GTPγS binding assay at the hH₄R, the mH₄R and the rH₄R and reported in literature.

Reference data are taken from (unless otherwise noted, α values referred to histamine = 1.0): afunctional [35S]GTPγS-binding assay on Sf9 cell membranes co-expressing the hH4R, mH4R or rH4R+Giα2+ β1γ2; b,c,dSteady-state [32P]GTPase assay on Sf9 cell membranes co-expressing: hH4R-RGS19+ Giα2+ β1γ2b[43], hH4R-GAIP+Giα2+ β1γ2, rH4R or mH4R+Giα2+ β1γ2+ GAIP d[23], hH4R+Giα2+ β1γ2c (α value of ST-1012 referred to thioperamide = −1.0, [39]); ecalcium mobilization assay in 293-EBNA cells transiently co- expressing the hH4R, mH4R or rH4R with Gqi5[20]; f,g,hcalcium mobilization assay in HEK293 cells stably co-expressing the hH4R, mH4R or rH4R with Gqi5f[46], g[44], h[45]; i,j,k,lCRE-β-galactosidase reporter gene assay in SK-N-MC cells stably co-expressing: the hH4R [40]–[42] or the mH4R k[57] with the CRE-β-galactosidase reporter gene; mCRE-luciferase reporter gene assay in HEK293T cells, transiently co-expressing the hH4R with the CRE-controlled luciferase reporter gene [27]; lSRE-luciferase reporter gene assay in HEK293 cells, co-expressing the human, mouse or rat H4R+SRE-luciferase+Gαqi chimeric G-protein [57].