Multiple forms of angiotensin II receptors in rat tissues.
Angiotensin II (AII) receptors were identified in rat tissue membranes by specific binding of 125I-labelled AII. Using an isoelectric focusing technique, two forms of the high-affinity AII receptor were identified in rat adrenal zona glomerulosa and liver membranes. These migrated to isoelectric points (pI) 6.8 and 6.7. Two low-affinity forms migrated to pI 6.5 and 6.3. The two high-affinity forms were in greatest abundance in the zona glomerulosa, while the low-affinity pI 6.5 isoform was predominant in liver membranes. In uterine membranes both low-affinity isoforms were observed, but there was only one of the high-affinity forms (pI 6.7). Concentrations of AII receptor isoforms were increased in the zona glomerulosa of sodium-deprived rats. Reduction of disulphide bridges with dithiothreitol (DTT) had different effects on the various AII receptor isoforms. Thus 1 mmol DTT/1 caused a twofold increase in 125I-labelled AII binding in zona glomerulosa membranes. DTT produced no appreciable differences in specific AII binding in uterine membranes, whereas there was a 50% reduction of binding in liver membranes. At 20 mmol/l, DTT greatly decreased AII binding in all tissues. The data suggest the existence of multiple forms of AII receptors which may have different functions.
Jimenez
E
E
Department of Biochemistry and Molecular Biology, University of Malaga, Spain.
Marsigliante
S
S
Barker
S
S
Hinson
J P
JP
Vinson
G P
GP
D000818:Animals; D001665:Binding Sites; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D007525:Isoelectric Focusing; D008099:Liver / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure; D014599:Uterus / Q000737:chemistry* / Q000378:metabolism; D015384:Zona Glomerulosa / Q000737:chemistry* / Q000378:metabolism
D011945:Receptors, Angiotensin; D004229:Dithiothreitol