Characterisation of the melanocortin 4 receptor by radioligand binding.
The DNA encoding the human melanocortin 4 receptor was expressed in COS (CV-1 origin, SV 40) cells and its radioligand binding properties was tested by using the [125I][Nle4, D-Phe7] alpha-melanocyte stimulating hormone (MSH). The radioligand was found to bind to a single saturable site with a Kd of 3.84 +/- 0.57 nmol/l in the MC4 receptor expressing cells. The order of potency of a number of substance competing for the [125I][Nle4, D-Phe7] alpha-MSH binding was the following; [Nle4, D-Phe7] alpha-MSH > [Nle4]-alpha-MSH > beta-MSH > desacetyl-alpha-MSH > alpha-MSH > ACTH (1-39) > ACTH (4-10) > gamma 1-MSH > gamma 2-MSH. This order of potency is unique for the melanocortin 4 receptor when compared to our previously published data for the other melanocortin receptor subtypes. Most notably the melanocortin 4 receptor shows highest affinity for beta-MSH, among the endogenous MSH-peptides. Furthermore the melanocortin 4 receptor shows very low affinity for the gamma-MSH peptides. This distinguishes the melanocortin 4 receptor from the melanocortin 3 receptor, which is the other major central nervous system melanocortin-receptor, as melanocortin 3 receptor shows high affinity for gamma-MSH. Our finding might indicate a specific role for beta-MSH for the melanocortin 4 receptor.
Schiöth
H B
HB
Department of Pharmaceutical Pharmacology, Uppsala University, Sweden.
Muceniece
R
R
Wikberg
J E
JE
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D019556:COS Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism; D008969:Molecular Sequence Data; D011869:Radioligand Assay; D018043:Receptors, Corticotropin / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D044101:Receptors, Melanocortin; D014162:Transfection; D000521:alpha-MSH / Q000031:analogs & derivatives / Q000378:metabolism
D018043:Receptors, Corticotropin; D044101:Receptors, Melanocortin; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-; D000324:Adrenocorticotropic Hormone; D009074:Melanocyte-Stimulating Hormones