0000000000329543
AUTHOR
Said Abd Alla
Ligand-induced phosphorylation/dephosphorylation of the endogenous bradykinin B2 receptor from human fibroblasts.
We have studied the ligand-induced phosphorylation/dephosphorylation of the bradykinin B2 receptor endogenously expressed in human HF-15 fibroblasts. An antiserum (AS346) to a synthetic peptide (CRS36), derived from the extreme carboxyl terminus of the human B2 receptor, precipitated the receptor from solubilized membranes of HF-15 cells that had been labeled with [32P]orthophosphate. A low basal level of B2 receptor phosphorylation was found in the absence of a ligand. Stimulation of the cells with the B2 receptor agonists bradykinin, [Lys0,Hyp3]bradykinin, kallidin, and T-kinin resulted in a rapid and efficient phosphorylation of the receptor. The B2 receptor antagonist HOE140 and the B1 …
Mapping of the high molecular weight kininogen binding site of prekallikrein. Evidence for a discontinuous epitope formed by distinct segments of the prekallikrein heavy chain.
Prekallikrein, a glycoprotein involved in contact phase activation, circulates in plasma in the form of a binary complex with high molecular weight kininogen (H-kininogen). The binding to H-kininogen is mediated by the prekallikrein heavy chain consisting of four repetitive domains, A1-A4. To define more precisely the region(s) involved in kininogen binding, we have employed an affinity cross-linking strategy with a synthetic peptide of 31 residues which mimics the prekallikrein binding site of H-kininogen. Cross-linking of the radiolabeled peptide to (pre)kallikrein revealed a binding segment in the NH2-terminal portion of the prekallikrein heavy chain; another binding segment was located …
Extracellular Domains of the Bradykinin B2 Receptor Involved in Ligand Binding and Agonist Sensing Defined by Anti-peptide Antibodies
Many of the physiological functions of bradykinin are mediated via the B2 receptor. Little is known about binding sites for bradykinin on the receptor. Therefore, antisera against peptides derived from the putative extracellular domains of the B2 receptor were raised. The antibodies strongly reacted with their corresponding antigens and cross-reacted both with the denatured and the native B2 receptor. Affinity-purified antibodies to the various extracellular domains were used to probe the contact sites between the receptor and its agonist, bradykinin or its antagonist HOE140. Antibodies to extracellular domain 3 (second loop) efficiently interfered, in a concentration-dependent manner, with…
Structural features of the human bradykinin B2 receptor probed by agonists, antagonists, and anti-idiotypic antibodies
The human bradykinin B2 receptor belongs to the family of G-protein-coupled receptors. To characterize the receptor protein, we have solubilized the membranes of cultured human foreskin fibroblasts bearing the B2 receptor. Affinity cross-linking of the solubilized receptor with the labeled agonist, 125I-Tyr0-bradykinin, or the labeled antagonist, 125I-(4-hydroxy-phenyl-propionyl)-HOE140, revealed major bands of apparent molecular mass of 69 kDa in SDS-polyacrylamide gel electrophoresis under reducing conditions, and of 59 kDa under non-reducing conditions. A 1000-fold molar excess of each of the unlabeled ligands quenched the specific labeling suggesting that the agonist and the antagonist …