Premium
Pharmacological characterization of a novel non‐AT1, non‐AT2 angiotensin binding site
Author(s) -
Swindle Jamala D,
Santos Kira L,
Speth Robert C
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb407
Subject(s) - radioligand , binding site , angiotensin ii , angiotensin ii receptor type 1 , receptor , angiotensin iii , chemistry , renin–angiotensin system , neuropeptide , antagonist , radioligand assay , ligand binding assay , ic50 , medicine , endocrinology , biology , biochemistry , in vitro , blood pressure
The recent discovery of a novel non‐AT1, non‐AT2 binding site for angiotensins in the rat brain and testis has catalyzed efforts to purify and characterize this protein. To assess the specificity of this binding site for angiotensins, various neuropeptides were evaluated with competition binding assays in brain and testis using 125 I‐Sar 1 , Ile 8 angiotensin II (Ang II) as the radioligand in the presence of saturating concentrations of AT 1 and AT 2 receptor antagonists and 100 μM parachloromercuribenzoate. Primary screening of 25 neuropeptides at 10 uM concentration revealed seven peptides that inhibited > 50%. Orphanin and two of its congeners (tyr 1 , and tyr 14 ) exhibited IC50 values ~ 1–5 μM in the brain and testis. Sar 1 ,thr 8 Ang II an Ang II antagonist showed high affinity for the binding site in brain and testis, consistent with previous observations of high affinity for Sar 1 ,Ile 8 Ang II. Ang I Pro 11 ,D‐Ala 12 moderately inhibited 125 I‐Sar 1 , Ile 8 Ang II binding in brain and testis at 10 μM confirming the preference of this binding site for Ang II receptor‐active peptides. The selective neurolysin inhibitor Pro‐Ile, was inactive at 10 μM. These results further establish the specificity of this novel non‐AT 1 , non‐AT 2 binding site for angiotensins II and III and suggest that this protein is heretofore uncharacterized. Supported by NHLBI HL‐096357.