Abstract
The molecular recognition theory predicts that binding domains of peptide hormones and their corresponding receptor binding domains evolved from complementary strands of genomic DNA, and that a process of selective evolutionary mutational events within these primordial domains gave rise to the high affinity and high specificity of peptide hormone-receptor interactions observed today in different peptide hormone-receptor systems. Moreover, this theory has been broadened as a general hypothesis that could explain the evolution of intermolecular protein-protein and intramolecular peptide interactions. Applying a molecular cloning strategy based on the molecular recognition theory, we screened a rat kidney cDNA library with a vasopressin (AVP) antisense oligonucleotide probe, expecting to isolate potential AVP receptors. We isolated a rat kidney cDNA encoding a functional V1-type vasopressin receptor. Structural analysis identified a 135 amino acid-long polypeptide with a single transmembrane domain, quite distinct from the rhodopsin-based G protein-coupled receptor superfamily. Functional analysis of the expressed V1-type receptor in Cos-1 cells revealed AVP-specific binding, AVP-specific coupling to Ca2+ mobilizing transduction system, and characteristic V1-type antagonist inhibition. This is the second AVP receptor cDNA isolated using AVP antipeptide-based oligonucleotide screening, thus providing compelling evidence in support of the molecular recognition theory as the basis of the evolution of this peptide hormone-receptor system, as well as adds molecular complexity and diversity to AVP receptor systems.
Highlights
Arginine-vasopressin (AVP) is a nonapeptide hormone with a diverse spectrum of biological effects in almost every organ system
The molecular recognition theory (MRT) further implies that peptide hormones and corresponding receptors evolved from complementary strands of genomic DNAs
The mRNAs were detected in all tissues tested with the following relative abundance: rat aortic smooth muscle cells (A-10 cells, ATCC) Ͼ adrenal gland (Adr.Gl.) Ͼ pulmonary vascular tissue (Lung Vasc.) ϭ rat aortic tissue (Ao) Ͼ brain ϭ heart Ͼ kidney Ͼ skeletal muscle (Sk.m.) ϭ lung ϭ liver
Summary
Arginine-vasopressin (AVP) is a nonapeptide hormone with a diverse spectrum of biological effects in almost every organ system It is involved in salt and water balance in the kidney [1]; increased glycogenolysis and gluconeogenesis in the liver [1]; chronotrophy and inotropy of the heart [1]; increased fluid secretion in the ciliary body and blood–brain barrier [1]; modulation of specific neuronal activation and animal behavior, memory retention, in the central nervous system [1]; paracrine regulation of gonadal functions [1]; and regulation of blood pressure [2,3,4]. Materials and Methods: Applying a molecular cloning strategy based on the molecular recognition theory, we screened a rat kidney cDNA library with a vasopressin (AVP) antisense oligonucleotide probe, expecting to isolate potential AVP receptors
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