Vasopressin antisense peptide interactions with the V1 receptor

Peptide self-aggregation and peptide complementarity as bases for the evolution of peptide receptors: a review

This paper reviews the three major theories of peptide receptor evolution: (1) Dwyer's theory that peptide receptors evolved from self-aggregating peptides; (2) Root-Bernstein's theory that peptide receptors evolved from functionally and structurally complementary peptides; and (3) Blalock's theory that receptors evolved from hydropathically complementary sequences encoded in the antisense strand of the DNA encoding each peptide. The evidence to date suggests that the co-yevolution of peptides and their receptors is strongly constrained by one or more of these physicochemically based mechanisms, which argues against a random or frozen accident' model. The data also suggest that structure and function are integrally related from the earliest steps of receptor-ligand evolution so that peptide functionality is non-random and highly conserved in its origin. The result is a molecular paleontology' that reveals the evolutionary constraints that shaped the interaction of structure and function.

Molecular complementarity III. peptide complementarity as a basis for peptide receptor evolution: a bioinformatic case study of insulin, glucagon and gastrin

Dwyer has suggested that peptide receptors evolved from self-aggregating peptides so that peptide receptors should incorporate regions of high homology with the peptide ligand. If one considers self-aggregation to be a particular manifestation of molecular complementarity in general, then it is possible to extend Dwyer's hypothesis to a broader set of peptides: complementary peptides that bind to each other. In the latter case, one would expect to find homologous copies of the complementary peptide in the receptor. Thirteen peptides, 10 of which are not known to self-aggregate (amylin, ACTH, LHRH, angiotensin II, atrial natriuretic peptide, somatostatin, oxytocin, neurotensin, vasopressin, and substance P), and three that are known to self-aggregate (insulin, glucagon, and gastrin), were chosen. In addition to being self-aggregating, insulin and glucagon are also known to bind to each other, making them a mutually complementary pair. All possible combinations of the 13 peptides and the extracellular regions of their receptors were investigated using bioinformatic tools (a total of 325 combinations). Multiple, statistically significant homologies were found for insulin in the insulin receptor; insulin in the glucagon receptor; glucagon in the glucagon receptor; glucagon in the insulin receptor; and gastrin in gastrin binding protein and its receptor. Most of these homologies are in regions or sequences known to contribute to receptor binding of the respective hormone. These results suggest that the Dwyer hypothesis for receptor evolution may be generalizable beyond self-aggregating to complementary peptides. The evolution of receptors may have been driven by small molecule complementarity augmented by modular evolutionary processes that left a "molecular paleontology" that is still evident in the genome today. This "paleontology" may allow identification of peptide receptor sites.

The antisense homology box: a new motif within proteins that encodes biologically active peptides

Amphiphilic peptides approximately fifteen amino acids in length and their corresponding antisense peptides exist within protein molecules. These regions (termed antisense homology boxes) are separated by approximately fifty amino acids. Because many sense-antisense peptide pairs have been reported to recognize and bind to each other, antisense homology boxes may be involved in folding, chaperoning and oligomer formation of proteins. The antisense homology box-derived peptide CALSVDRYRAVASW, a fragment of human endothelin A receptor, proved to be a specific inhibitor of endothelin peptide (ET-1) in a smooth muscle relaxation assay. The peptide was able to block endotoxin-induced shock in rats as well. Our finding of endothelin receptor inhibitor among antisense homology box-derived peptides indicates that searching proteins for this new motif may be useful in finding biologically active peptides.

Studies on T-cell receptors involved in experimental autoimmune encephalomyelitis using the complementary peptide recognition approach

Based upon Blalock's complementary recognition approach, a complementary or antisense peptide (CP) was designed to the experimental autoimmune encephalomyelitis (EAE) epitope peptide, rat myelin basic protein (MBP) peptide 72-82. This peptide (EAE CP) was shown to have some sequence similarities to T-cell receptors (TCR) and MHC II molecules in a sequence homology search. Solid-phase binding assays demonstrated specific and high affinity binding (3 and 4 microM) between the EAE CP and the rat and guinea pig EAE epitope peptides (Rt72-82 and Gp69-82), respectively. This EAE CP was also found to be immunogenic in rats in an ear swelling test for delayed type hypersensitivity (DTH) reactions and an ELISA for antibody responses. However, a rabbit antibody generated to EAE CP was shown to be unable to stain the V beta 8+ EAE susceptible T-cells in immunofluorescence analyses. This EAE CP was also used in attempts to down-regulate EAE and the results showed that prior immunization with EAE CP in complete Freund's adjuvant could not prevent the Lewis rats from developing EAE. Although the data on sense-antisense peptide interaction were positive and the EAE CP was immunogenic, the inability of EAE CP to regulate EAE indicates that the CP approach may not be generally applicable.

Canine parietal cell binding by antibodies to the complementary peptide of somatostatin

Using antibodies to a complementary peptide of somatostatin, putative somatostatin binding proteins were characterized on canine parietal cells. A synthetic peptide (S-C1) was derived from the complementary mRNA sequence for somatostatin-14. Antiserum containing antibodies to S-C1 inhibited competitively 125I-Tyr11-somatostatin binding to canine oxyntic mucosal membranes. Canine parietal cell preparations were incubated with carbachol in the presence or absence of somatostatin and antisera to S-C1. Antibodies to S-C1 produced a decrease in carbachol-stimulated 14C-aminopyrine uptake comparable with that produced by 10(-6) M somatostatin. In immunocytochemical studies by light microscopy, antibodies to S-C1 produced positive staining of parietal cells throughout the oxyntic gland area. By electron microscopy using immunogold techniques, binding by antibodies to somatostatin C-1 was localized ultrastructurally to basolateral and intracellular membranes and to secretory canalicular membranes of parietal cells. These studies support the conclusion that antibodies to the somatostatin complementary peptide demonstrate properties similar to those of somatostatin in that they inhibit carbachol-stimulated aminopyrine uptake and 125I-somatostatin binding. Furthermore, these antibodies localize to specific regions on plasma membranes of parietal cells, which may represent somatostatin binding sites.

Lack of interaction of vasopressin with its antisense peptides: a functional and immunological study

The peptide encoded in the 5' to 3' direction by rat vasopressin complementary RNA, rat PVA (H-Ser-Ser-Trp-Ala-Val-Leu-Glu-Val-Ala- OH) and the corresponding bovine PVA (H-Ala-Pro-Trp-Ala-Val-Leu-Glu-Val-Ala-OH) were investigated with respect to their interaction with [8-arginine] vasopressin (AVP) and V2 vasopressin receptor binding and function. Rat or bovine PVA did neither affect the binding of the hormone to the V2 receptor of bovine kidney membranes and LLC-PK1 pig kidney cells nor influence the AVP-induced cAMP-production in LLC-PK1 cells. Rat PVA was further investigated by the use of vasopressin-specific polyclonal and monoclonal antibodies with different affinity and epitope specificity. Consistent with receptor binding studies no inhibition of [3H]AVP-binding in fluid- or solid-phase antibody binding tests after preincubation with PVA was found. Direct interaction of rat PVA and [3H]AVP measured on solid surface was not observed in contrast to specific binding of the hormone with NP II and antibodies. In our study no evidence for an interaction of AVP and its antisense peptides was found.

Isolation and characterization of the rat liver AVP receptor using [125I][d(CH2)5'sarcosine7]AVP

1. A vasopressin (AVP) binding protein was purified from rat liver membranes by an improved method using [125I][d(CH2)5'Sarcosine7]AVP, a selective V1 AVP radioligand and a combination of CHAPS solubilization, gel filtration, lectin affinity and FPLC ion exchange chromatography. 2. The purified protein exhibited a maximum binding activity of 2480 pmol/mg protein with a KD of 4.5 nmol/L, which corresponds to a purification of approximately 26,700-fold. The molecular weight of this protein was 70,000 Da. 3. The binding of [125I][d(CH2)5'Sarcosine7]AVP to the solubilized membranes was dependent on the protein concentration, and was inhibited by the unlabelled peptides [d(CH2)5'Sarcosine7]AVP, AVP, and to a lesser degree by peptides with high V2 receptor affinity, such as 1-desamino-D-AVP and [d(CH2)5'D-Ileu2-Ileu4]AVP. 4. In addition, an AVP anti-idiotypic monoclonal antibody bound to both the partially purified and purified lectin affinity AVP binding protein in a concentration-dependent manner. These results indicate that the purified protein displays similar characteristics to the liver membrane-bound AVP V1 receptor.