Figure 3.

MCHR2 is a receptor for MCH. (A) MCH stimulates a transient increase in intracellular Ca²⁺ similar to that resulting from MCH activation of MCHR1. CHO cells were transfected with MCHR2 or MCHR1 expression plasmids. The intracellular Ca²⁺ levels were measured with an aequorin luminescent assay (Materials and Methods). (B) MCH activated MCHR2 with an EC₅₀ comparable to that observed with MCHR1 in transiently transfected HEK293 cells. (C) Specific activation of MCHR2 by MCH. MCH or MCH-related peptides were tested for activation of MCHR2 receptor by the aequorin assay. Only MCH, salmon MCH, and the MCH analog [Phe¹³, Tyr¹⁹]-MCH [MCH (P/T)] induced a Ca²⁺ increase in MCHR2-transfected HEK293 cells. SST14, somatostatin-14; CS14, cortistatin-14; αMSH, α-melanotropin; NEI, neuropeptide-EI (MCH-precursor-derived peptide).