Two structurally distinct forms of the angiotensin receptor AT-1 (AT-1a and AT-1b) were identified in the mouse genome, exhibiting similar binding profiles but differing in their intracellular domains.
The identification of two distinct mouse AT-1 receptor isoforms with similar binding properties suggests potential differences in their intracellular regulation or signal transduction.
We report the existence of two structurally distinct forms of the angiotensin receptor AT-1 in the mouse. A Balb/c mouse genomic library was screened by homology screening with a polymerase chain reaction (PCR) amplified probe. Restriction mapping and sequencing of the isolated genes revealed the presence of two receptor isoforms, here named the mouse AT-1a and AT-1b receptors, containing 22 different amino acids. Receptor binding studies performed on COS-7 cells transfected with the two receptors revealed that they had similar binding profiles for angiotensin II, angiotensin III and AT-1 or AT-2 specific antagonists. Because many of the structural differences were in the carboxy terminal putative intracellular domain, we speculate that these isoforms may differ in their regulation, signal transduction, or desensitization mechanisms.
Sasamura et al. (1992) studied this question. Cloning and expression of AT-1a and AT-1b receptors was evaluated on Receptor binding profiles. Two structurally distinct forms of the angiotensin receptor AT-1 (AT-1a and AT-1b) were identified in the mouse genome, exhibiting similar binding profiles but differing in their intracellular domains.