Characterization and localization of a novel neuroreceptor for the peptide sarafotoxin.
We have recently shown that the rat atrium and brain contain specific high affinity receptors for the novel snake vasoconstrictor peptide sarafotoxin-b (SRTXb), and demonstrated toxin-induced phosphoinositide hydrolysis. Here we report on the characteristics of 125I-SRTXb receptors and their regional distribution in rat brain. 125I-SRTX receptors in the rat brain bind the toxin rapidly and with high affinity. The binding was not inhibited by ligands of known neurotransmitter receptor and ion channels. 125I-SRTX receptors have a distinctive regional distribution. The highest densities were observed in the cerebellum, thalamus and hypothalamus (850, 550 and 450 fmol/mg protein, respectively) and the lowest densities in the caudate and cerebral cortex (82 and 62 fmol/mg protein, respectively). Taken together our results suggest that mammalian brains contain a hitherto undetected neuroreceptor that may operate in neurotransmission with a "SRTX-like" brain peptide, similar to the SRTX homologous vasoconstrictor peptide of the mammalian endothelium endothelin.
Ambar
I
I
Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
Kloog
Y
Y
Kochva
E
E
Wollberg
Z
Z
Bdolah
A
A
Oron
U
U
Sokolovsky
M
M
D000818:Animals; D001923:Brain Chemistry; D001933:Brain Stem / Q000032:analysis; D002531:Cerebellum / Q000032:analysis; D002540:Cerebral Cortex / Q000032:analysis; D006624:Hippocampus / Q000032:analysis; D007031:Hypothalamus / Q000032:analysis; D007457:Iodine Radioisotopes; D008297:Male; D009830:Olfactory Bulb / Q000032:analysis; D051381:Rats; D011950:Receptors, Cholinergic / Q000032:analysis*; D018000:Receptors, Peptide; D013788:Thalamus / Q000032:analysis; D014018:Tissue Distribution; D014757:Viper Venoms / Q000378:metabolism
D007457:Iodine Radioisotopes; D011950:Receptors, Cholinergic; D018000:Receptors, Peptide; D014757:Viper Venoms; C058085:sarafotoxin receptor; C057354:sarafotoxins s6