Cloning of two mouse genes encoding alpha 2-adrenergic receptor subtypes and identification of a single amino acid in the mouse alpha 2-C10 homolog responsible for an interspecies variation in antagonist binding.
Molecular cloning and ligand binding studies have shown the alpha 2 class of adrenergic receptor (alpha 2-AR) to be a family of at least three related subtypes in humans. These studies have not, however, identified distinct subtype-specific functions for these receptors in vivo. It should be possible to extend the analysis of alpha 2-AR subtype function to the animal level through the use of experimental mammalian embryology in mice. To begin this process, we have isolated two mouse genomic clones encoding alpha 2-AR subtypes and expressed these genes in COS-7 cells for binding studies. Sequence homology and ligand binding data allow the assignment of one clone (M alpha 2-4H) as the mouse homolog of the human alpha 2-C4 subtype. The other clone (M alpha 2-10H) closely resembles the human alpha 2-C10 subtype in sequence but binds with significantly lower affinity to yohimbine and rauwolscine, members of a distinct class of bulky alpha 2-selective antagonists commonly used to evaluate alpha 2-AR function in vivo. To define the domain(s) responsible for this unusual binding property, we constructed a series of M alpha 2-10H/human alpha 2-C10 chimeric receptors. Analysis of these receptors identified a conservative Cys201 to Ser201 change in the fifth transmembrane domain of M alpha 2-10H as being responsible for the low affinity of the mouse receptor for yohimbine.
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Department of Molecular and Cellular Physiology, Stanford University, California 94305.
Daunt
D
D
Barsh
G
G
Chruscinski
A
A
Kobilka
B
B
D000317:Adrenergic alpha-Antagonists / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA; D007093:Imidazoles / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011942:Receptors, Adrenergic, alpha / Q000235:genetics* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D015016:Yohimbine / Q000378:metabolism
D000317:Adrenergic alpha-Antagonists; D000596:Amino Acids; D007093:Imidazoles; D011942:Receptors, Adrenergic, alpha; C050701:atipamezole; D015016:Yohimbine; D004247:DNA