The rat homologue of the bovine alpha 1c-adrenergic receptor shows the pharmacological properties of the classical alpha 1A subtype.
The cDNA for the rat alpha 1c-adrenergic receptor (AR) has been cloned using a probe derived from the bovine alpha 1c-AR sequence. Clone rB7a has a 2.6-kilobase insert with a 1390-base pair open reading frame and encodes a receptor of 466 amino acids. The cloned receptor has 91% amino acid identity with the bovine alpha 1c-AR. The rat alpha 1c-AR mRNA was detected in tissues known to be enriched for the alpha 1A-AR subtype, including vas deferens, heart, kidney, and hippocampus. Rat alpha 1c-AR mRNA was absent from liver and spleen when assayed by Northern blot analyses and RNase protection assays. In COS-7 cells transfected with cDNAs encoding the three rat alpha 1-ARs, WB-4101 and benoxathian had similar binding affinities for the alpha 1a/d-AR and the alpha 1c-AR and 10-fold lower affinities for the alpha 1b-AR. The affinity of 5-methylurapidil was found to be 10- and 30-fold higher at the alpha 1c-AR than at the alpha 1a/d- and alpha 1b-ARs, respectively. (S)-(+)-Niguldipine was found to have high affinity for the rat alpha 1c-AR, with 42- and 22-fold lower affinity at the alpha 1a/d- and alpha 1b-ARs, respectively. Treatment of intact transfected COS-7 cells with chlorethylclonidine resulted in the inactivation of 19% of the alpha 1c-ARs, in contrast to 72% and 85% inactivation of the alpha 1a/d- and alpha 1b-ARs, respectively. Similarly to the other two alpha 1-ARs, the rat alpha 1c-AR is coupled to the activation of phospholipase C. Our data suggest that the rat alpha 1c-AR cDNA encodes an alpha 1-AR with the pharmacological properties previously defined for the alpha 1A subtype found in tissues.
Laz
T M
TM
Synaptic Pharmaceutical Corporation, Paramus, New Jersey 07652.
Forray
C
C
Smith
K E
KE
Bard
J A
JA
Vaysse
P J
PJ
Branchek
T A
TA
Weinshank
R L
RL
D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D002417:Cattle; D002460:Cell Line; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression / Q000235:genetics; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016366:Open Reading Frames; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000737:chemistry* / Q000145:classification / Q000187:drug effects / Q000235:genetics; D012260:Ribonucleases / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D010738:Type C Phospholipases / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018076:DNA, Complementary; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D011942:Receptors, Adrenergic, alpha; C051731:chlorethylclonidine; D012260:Ribonucleases; D010738:Type C Phospholipases; D003000:Clonidine