title: Binding affinity of full-length and extracellular domains of recombinant human (pro)renin receptor to human renin when expressed in the fat body and hemolymph of silkworm larvae.
abstract: Transmembrane domains of some receptors have been found to be very important in the process of constitutive oligomerization, and in the stability and functioning of the receptor. In this study, full-length of human (pro)renin receptor (hPRR) and hPRR lacking cytoplasmic domain (hPRR-DeltaCD) were expressed in fat body of silkworm larvae, and the extracellular domain of hPRR (hPRR-DeltaTMDeltaCD) in hemolymph. Three forms of hPRR were used for investigation of the interaction between receptor and ligand using surface plasmon resonance (SPR). As a result, the cytoplasmic domain was not an essential requirement for binding affinity, but the transmembrane domain of hPRR was indispensable in the formation of functional hPRR. The dissociation equilibrium constants (K(D)) of purified hPRR and hPRR-DeltaCD were estimated to be 46 nM and 330 nM, respectively. No evidence of binding by the extracellular domain of hPRR located in hemolymph was found. However, the solubilized microsomal fraction of the extracellular domain of hPRR expressed in the fat body showed specific affinity, but lost its binding affinity after purification. Its binding affinity was recovered by mixing microsomal fraction of mock-injected fat body to the purified extracellular domain. It is probable that an artificial transmembrane domain stabilizes the extracellular domain of hPRR and native conformation may be structurally recovered. To our knowledge, these are the first findings describing the interaction of transmembrane and extracellular domains of hPRR with ligand and this may help towards the understanding of binding affinity of hPRR to ligand.
authors.affiliation: Shizuoka University, Ohya, Suruga-ku, Japan. dongningdu@hotmail.com
authors.forename: Dongning
authors.initials: D
authors.lastname: Du
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kato
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Suzuki
authors.forename: Enoch Y
authors.initials: EY
authors.lastname: Park
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D012831:Bombyx / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers; D005786:Gene Expression Regulation; D006458:Hemolymph / Q000378:metabolism; D006801:Humans; D007814:Larva; D008024:Ligands; D008861:Microsomes / Q000378:metabolism; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012083:Renin / Q000378:metabolism*; D020349:Surface Plasmon Resonance; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000093342:Prorenin Receptor
chemical_list: D020121:5' Untranslated Regions; C458319:ATP6AP2 protein, human; D017931:DNA Primers; D008024:Ligands; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D012083:Renin; D025262:Vacuolar Proton-Translocating ATPases; D000093342:Prorenin Receptor