Table 1.

Activities and potencies of peptide ligands on R1 and peptide/R1 chimeras

	Vehicle, -fold	Astressin, -fold	Urocortin
			-fold	EC60, nM
RI (wild type)	1.3  ± 0.2	2.5  ± 0.2	92  ± 11	0.21  ± 0.04
CRF(1–16)/R1ΔN	25  ± 4	26  ± 4	30  ± 3	—
CRF(17–41)/R1ΔN	1.2  ± 0.1	1.7  ± 0.3	51  ± 7	110  ± 20
CRF(1–16)/R1	1.1  ± 0.2	2.0  ± 0.3	76  ± 5	0.20  ± 0.1

Data are presented as mean ± SEM from 4–15 independent experiments, each performed in triplicate. The cAMP level is normalized in each experiment to that observed in the presence of 10 μM antalarmin. Because of the low level of urocortin stimulation of CRF(1–16)/R1ΔN, the EC₅₀ could not be determined.