Biomedical subjects

D J McCormick

Publications and source records attributed to D J McCormick.

At least 73 records · Page 4Linked to original sources

PubMed1992

Identification of hormone-binding regions of the luteinizing hormone/human chorionic gonadotropin receptor using synthetic peptides.

A comprehensive series of overlapping synthetic peptides have been used to study the relationship between the primary structure of the ovarian receptor for LH/human CG (hCG) and hormone binding. Twenty-four consecutive, overlap peptides that replicate the entire extracellular domain of the rat luteal receptor have been synthesized by standard solid-phase techniques on an automated synthesizer. Eight additional peptides from the extracellular domain and three peptides replicating the putative extracellular loop regions have also been synthesized. Each peptide was evaluated in RRAs for interaction with hCG by measuring its ability to competitively inhibit binding of 125I-hCG to membrane receptor. Twelve peptides were found to be potent in RRAs and caused a reduction of half-maximal binding of 125I-hCG at concentrations of 10-250 x 10(-6) M. The 12 active peptides (and adjacent inactive peptides) defined at least 4 independent receptor regions that can interact with hormone. One site near the NH2-terminus was localized to receptor residues Arg21-Pro38. Two more sites of hormone interaction were identified by peptides replicating residues Arg102-Thr115 and Tyr253-Phe272. A fourth binding region was identified in the third putative extracellular loop, replicated by rat luteal receptor peptide Lys573-Lys583. The amino acid sequences of the four active rat LH/hCG receptor regions were aligned and compared with published sequences for other glycoprotein hormone receptors. Three regions (Arg102-Thr115, Tyr253-Phe272, and Lys573-Lys583) showed high sequence homology with the human LH/hCG receptor, human TSH receptor, and rat FSH receptor and may represent contact sites for the alpha-subunit of hormone. The other binding region, Arg21-Pro38 had low sequence homology with the other glycoprotein hormone receptors and is postulated to be a binding determinant for beta-hCG/LH. This report demonstrates that synthetic overlap peptides of confirmed sequence can be used to successively identify hormone interaction sites of glycoprotein hormone receptors.

Amino Acid Sequence↗

PubMed1992

Muscle acetylcholine receptors complexed with autologous IgG reflect seropositivity but not necessarily in vivo binding.

The diagnosis of acquired myasthenia gravis (MG) in apparently seronegative individuals is aided by finding immunoglobulin complexed to acetylcholine receptors (AChR) and a reduction in the number of binding sites for alpha-bungarotoxin (alpha-BTx) in nerve-muscle biopsies. In this study, we found that anti-AChR antibodies in extracellular fluids can complex with cytoplasmic epitopes of AChR in the process of muscle extraction. When normal muscle was briefly exposed to antibodies (greater than or equal to 0.3 nmol/l) in the initial step of tissue homogenization (before detergent extraction), membranous AChR became complexed with IgG. This was so even with a nonmyasthenogenic monoclonal antibody specific for the alpha-subunit's presumptive cytoplasmic segment 366-389. We also found that antibodies reactive with AChR's alpha-BTx binding region can significantly lower apparent yields of alpha-BTx binding sites extracted from muscle. Thus, the finding of IgG complexed to AChR extracted from biopsied muscle does not necessarily reflect in vivo binding but, nevertheless, is a sensitive indicator of AChR seropositivity in patients suspected to have MG.

Animals↗

PubMed1992

Human liver dehydroepiandrosterone sulfotransferase: molecular cloning and expression of cDNA.

Sulfation is an important pathway in the metabolism of many hormones and drugs. Human liver contains at least three well characterized sulfotransferase (ST) enzymes, i.e., dehydroepiandrosterone (DHEA) ST and two forms of phenol sulfotransferase (PST). Our goal was to purify, to obtain partial amino acid sequence for, and to clone and express cDNA for human liver DHEA ST. Polymerase chain reaction primers were designed on the basis of homology among rat liver hydroxysteroid ST, rat liver PST, and bovine estrogen ST. These primers amplified a unique sequence from human liver cDNA, and this polymerase chain reaction product was used to screen a human liver cDNA library. Two clones were isolated that contained identical open reading frames, of 855 nucleotides, that encoded a protein of 285 amino acids. The deduced amino acid sequence of the encoded protein included two separate 27- and 23-amino acid sequences that were identical to those obtained by microsequencing of proteolytic fragments from purified human liver DHEA ST. Translation, in a rabbit reticulocyte lysate system, of mRNA transcribed in vitro from the two cDNA clones resulted in a 35-kDa translation product that comigrated with purified human liver DHEA ST during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This translation product also catalyzed the sulfation of DHEA but not the sulfation of model substrates for the two forms of PST found in human liver. The two cDNA clones were also used to create expression constructs with the eukaryotic expression vector P91023(B), and these constructs were used to transfect COS-1 cells. The transfected cells expressed a high level of DHEA ST activity, and this enzyme activity displayed a pattern of inhibition by the ST inhibitor 2,6-dichloro-4-nitrophenol identical to that of human liver DHEA ST. Cloning of cDNA for this important human sulfate-conjugating enzyme will enhance understanding of the relationship between DHEA ST and other human liver STs, as well as ST enzymes in other species.

Amino Acid Sequence↗

PubMed1991

Further characterization of the receptor-binding region of the thyroid-stimulating hormone alpha subunit: a comprehensive synthetic peptide study of the alpha-subunit 26-46 sequence.

Previously, using a synthetic peptide strategy, we determined that the region of the common glycoprotein hormone alpha subunit between residues 26 and 46 is a site of interaction of the hormone with the thyroid membrane-bound receptor for thyroid-stimulating hormone (TSH). We have undertaken to identify further the specific residues within this 21-amino acid span that are critical in hormone receptor binding. We synthesized three nested sets of peptide, two in which we systematically truncated the amino-terminal region of the sequence and another in which we truncated the carboxyl-terminal region, and we synthesized a fourth nested set in which we systematically substituted alanine for the native residues from the region of highest activity. Each peptide was tested in a TSH radioreceptor assay for its ability to inhibit binding of 125I-labeled bovine TSH to porcine thyroid membranes. Removal either by truncation or alanine substitution, of several specific residues resulted in a significant reduction in the ability of the sequence to interact with receptor; these residues included Cys31, Cys32, Phe33, Arg35, Arg42, Lys44, and Lys45, suggesting that they are crucial for binding activity. Loss of activity also occurred with substitution for Gly30 and Ser34, but the reduction was less pronounced. Amino-terminal truncation of the sequence through Arg35 (leaving the alpha-subunit peptide 36-46) resulted in greater than 98% loss of activity of the sequence. We conclude that two distinct receptor binding regions lie within the alpha-subunit 26-46 sequence. The first lies between residues Gly30 and Arg35 and includes Cys31, Cys32, and Phe33 as important constituents, and the second region lies between residues Arg42 and Lys45 and includes Lys44 as an important residue and Ser43 as a less important component.

Amino Acid Sequence↗

PubMed1991

Structure-antinociceptive activity of neurotensin and some novel analogues in the periaqueductal gray region of the brainstem.

Neurotensin, an endogenous tridecapeptide, produces a potent, naloxone-insensitive antinociceptive response when it is microinjected into the periaqueductal gray region of the rat brainstem. In the present study, the ED50 for neurotensin in inducing antinociception was 1.5 nmol, two times more potent than morphine. We sought to find whether neurotensin's antinociceptive effects were mediated by the same receptor that mediates its other functions. We found that the structure-activity relationship of neurotensin-induced antinociception was different from that required for the stimulation of intracellular cyclic GMP production in neuroblastoma clone N1E-115 and the binding to N1E-115 cells, human brain tissue, or rat periaqueductal gray. These data suggest there exists a subtype of neurotensin receptors in neural tissue that mediates its antinociceptive actions.

Analgesics↗

PubMed1991

Residues in the alpha subunit of human choriotropin that are important for interaction with the lutropin receptor.

Synthetic peptides were used to probe the structure-function relationships between human choriotropin (hCG) and the lutropin (LH) receptor. Previously, a peptide region of the alpha subunit of hCG, residues 26-46, had been shown to inhibit binding of 125I-hCG to the LH receptor in rat ovarian membranes (Charlesworth, M.C., McCormick, D.J., Madden, B., and Ryan, R.J. (1987) J. Biol. Chem. 262, 13409-13416). To determine which residues are important for this inhibitory activity, peptides were truncated from either the amino or carboxyl terminus, or individual residues were substituted with alanine. The amino-terminal boundary was determined to be Gly-30 and the carboxyl-terminal boundary, Lys-44. This core peptide contained all the residues needed for full activity of the parent peptide 26-46. Arg-35 and Phe-33 were particularly important residues; when they were substituted with alanine, the peptide inhibitory potencies were decreased. Ser-43, Arg-42, Cys-32, and Cys-31 were also important but to a lesser degree. These results are consistent with predictions based on chemical and enzymatic modification studies and provide insight into which residues are important for interaction between hCG and the LH receptor.

Alanine↗

PubMed1991

Characterization of a purified chromatin acceptor protein (receptor binding factor 1) for the avian oviduct progesterone receptor.

The specific, high-affinity binding of the avian oviduct progesterone receptor (PR) with target-cell nuclei and chromatin has been shown to involve DNA complexed with specific chromatin acceptor proteins. One of these chromatin acceptor proteins has been partially purified and found to be a small hydrophobic protein with a broad pI of 5.0-6.0 [Goldberger, A., & Spelsberg, T. C., (1988) Biochemistry 27, 2103-2109]. This paper describes the final purification over 100,000-fold to apparent homogeneity of this candidate PR acceptor protein, termed the receptor binding factor 1 (RBF-1). When the avian genomic DNA is bound by RBF-1, saturable, high-affinity (KD approximately 2 x 10(-9) M) binding sites for PR are generated. RBF-1 has a unique, hydrophobic N-terminal sequence. The PR binding to the RBF-1-DNA complexes is shown to be dependent on an intact activated PR with which excess nonradiolabeled PR can compete. By use of a new, highly specific monoclonal antibody (mAb) to the RBF-1 with Western immunoblotting, RBF-1 was shown to be localized in the nucleus and to be tissue and species specific. Selective removal of the chromatin proteins containing RBF-1 results in the loss of the highest affinity class of PR binding sites. A second class of residual PR binding sites remains in the nucleoacidic protein (NAP), a complex of proteins more tightly bound to the DNA. This class of PR binding activity has been classified as the RBF-2. The RBF-1 is estimated to be 0.03% of the total chromatin protein with about 1.2 x 10(5) molecules/diploid cell.

Amino Acid Sequence↗

PubMed1991

An avidin-biotin-peroxidase assay to detect synthetic peptides bound to polystyrene plates.

The simple chemical method described for detecting synthetic peptides bound to polystyrene should facilitate interpretation of studies involving interactions of antibodies or solubilized major histocompatibility complex (MHC) molecules with immobilized peptide antigens. After its application to an ELISA plate, the peptide is biotinylated in situ and avidin-biotinylated horseradish peroxidase complex and substrate are added sequentially. For 36 of 43 peptides tested (11-27 residues long), a colored reaction product confirmed that the peptide was bound. In three of the seven instances of a negative result, peptides were positively detected by binding of antibody. Four instances remained in which it could not be determined whether the peptide did not bind to the plate or whether it was not biotinylated. On the other hand, the biotin-ABC assay positively detected peptide in 18 of 22 instances without evidence of antibody binding, implying seronegativity or a loss of antigenic conformation in the bound peptide. This general method should be applicable to assays of microbial antigens, autoantigens and allergens. Modification of the technique by use of biotin hydrazide should enable monitoring of the binding to polystyrene of carbohydrates, glycolipids or DNA.

Animals↗

PubMed1991

Purification of a nuclear protein (receptor binding factor-1) associated with the chromatin acceptor sites for the avian oviduct progesterone receptor.

The specific high affinity binding of the avian oviduct progesterone receptor (PR) to target cell nuclei and chromatin has been shown to involve DNA complexed with specific chromatin acceptor proteins. One of these chromatin acceptor proteins has been partially purified and found to be a small hydrophobic protein with a broad pI of 5.0-6.0 [Goldberger and Spelsberg (1988), Biochem. 27, 2103-2109]. Using western immunoblots with anti-RBF-1 polyclonal antibodies to monitor the purification, a 10 kD candidate acceptor protein, termed the Receptor Binding Factor-1 (RBF-1), has been purified to apparent homogeneity. RBF-1 has an amino acid composition consistent with a hydrophobic protein having an acidic pI and a unique N-terminal sequence. Two-dimensional polyacrylamide gel electrophoresis and high-performance capillary electrophoresis support the purity of a protein congruent to 10 kD in size, having an acidic pI, but with evidence of several differently charged isoforms. Phosphatase treatment provides evidence that charge heterogeneity may result from variable phosphorylation states. A role of this factor as a candidate "acceptor protein" in the chromatin acceptor sites for the avian oviduct PR is proposed.

Animals↗

PubMed1991

Identification of three extended antibody-binding segments in recombinant human muscle acetylcholine receptor alpha subunit extracellular domain 1-210.

The duplicated alpha subunits account for 40% of the total protein of the nicotinic acetylcholine receptor of muscle, and are implicated as targets for pathogenic autoantibodies in the neuromuscular disease myasthenia gravis (MG). This study reports some of the specificities of antibodies induced by a myasthenogenic recombinant protein (rH alpha 1-210) corresponding to the proposed extracellular domain of the alpha subunit of human acetylcholine receptor, residues 1-210. Antisera produced by immunizing rats, rabbits, and mice were tested with a panel of overlapping synthetic peptides (each 16 amino acids) comprising residues 1-216 of the human alpha subunit. IgG antibodies produced in all three species bound only to peptides that were clustered in three segments: segment I (residues 9-24); segment II (57-96 in rats, 57-88 in rabbits, and 57-80 in mice); and segment III (137-184 in rats, 145-184 in rabbits and mice). Monoclonal antibodies were produced by 41 independent hybridomas derived from three rats immunized with rH alpha 1-210; 12 reacted only with the recombinant or native protein, and 29 reacted additionally with peptides in segments II or III. Four mAbs bound to native human receptor; of these, three bound to peptides 57-72/65-80, 81-96, or 153-168, and one lacked peptide-binding activity. Lack of mAb reactivity with rat receptor precluded correlation of peptide reactivity with myasthenogenicity. Nevertheless, the data indicate that the human acetylcholine receptor's alpha subunit contains multiple sites in its extracellular domain that are potentially stimulatory for B cells.

Amino Acid Sequence↗

PubMed1991

Device interaction--antitachycardia pacemakers and defibrillators for sustained ventricular tachycardia.

We evaluated the combined use of permanent automatic antitachycardia pacemakers and implanted defibrillators in ten patients with recurrent monomorphic sustained ventricular tachycardia (VT). Pacemaker programming was VVI-T automatic burst in eight patients, VVI-T magnet mode in one patient, and VVI in one patient. Device interactions occurred in four patients, requiring changes in pacemaker programming. These included defibrillator multiple counting during pacing, inappropriate pacemaker bursts initiating VT, inappropriate reset of the pacemaker antitachycardia mode by defibrillation, defibrillator discharge after pacemaker VT termination, and defibrillator VT reinitiation. Two patients required pacemaker programming out of the antitachycardia mode, and two required a change in antitachycardia pacing parameters. Seven patients remain in automatic VVI-T and three in VVI modes. Mean follow-up is 13 months and all patients are alive. Thus, although pacemaker/defibrillator combinations function well for patients with more than one VT rate, device interactions occur frequently and may require pacemaker reprogramming or elimination of the overdrive mode. Combined use of these devices should be cautiously considered when single device therapy is unsatisfactory. Devices that combine both pacing and defibrillation features may reduce adverse interaction.

Algorithms↗

PubMed1991

The antigenic structure of the human glycoprotein hormone alpha-subunit: III. Solution- and solid-phase mapping using synthetic peptides.

Twenty-seven synthetic peptides, representing the entire structure of the human glycoprotein hormone alpha-subunit were used to map the antigenic structure of the alpha-subunit. Solution phase and solid phase assays were performed with these peptides and a panel of eight monoclonal antibodies (MAb). Two dominant regions were localized between residues 22-37 and 70-87. All eight antibodies recognized these regions, but differed somewhat with respect to whether they saw the more N-terminal, middle, or C-terminal portions of these regions. The sequence of residues 13-22 was recognized by three MAbs. The C-terminal region from residues 84-92 was recognized by three MAbs. All MAbs recognized conformational epitopes in that they reacted with two or more regions. Three MAbs (two against free alpha and one against human CG) have linear amino acid sequences as part of their conformational epitope.

Antibodies, Monoclonal↗

PubMed1990

Inhibition of thyrotropin binding to receptor by synthetic human thyrotropin beta peptides.

In order to study the structure and function relationships of the thyrotropin (TSH)-specific beta-subunit, we produced 11 synthetic overlapping peptides containing the entire 112-amino acid sequence of human beta TSH and tested them for activity in TSH radioreceptor assay using both human and porcine thyroid membranes. Synthetic peptides representing four regions of the beta-subunit demonstrated the ability to inhibit binding of 125I-bovine TSH to crude thyroid membranes. The peptide representing the -COOH terminus of the subunit (beta 101-112) possessed highest binding activity, inhibiting binding of labeled TSH with an EC50 of 80 microM. The remaining active peptides were: beta 71-85 (104 microM), beta 31-45 (186 microM), beta 41-55 (242 microM), and beta 1-15 (331 microM). Specificity of the binding activity was shown by the inability of the peptides representing the remainder of the subunit to inhibit binding of label and by the inability of any of the peptides to inhibit binding of 125I-epidermal growth factor to the same thyroid membranes. The low affinity of the peptides as compared with native hormone is in agreement with previous studies of synthetic alpha-subunit peptides and, further, suggests that the interaction of beta TSH with receptor is multifaceted, requiring cooperative binding of these sites for the observed high affinity of the whole hormone. These studies are in agreement with previous predictions of active regions by chemical modification but add two regions to the list, showing the utility of the synthetic peptide strategy in the study of peptide hormone structure-activity relationships.

Amino Acid Sequence↗

PubMed1990

Interaction of calmodulin with the calmodulin binding domain of the plasma membrane Ca2+ pump.

Peptides corresponding to the calmodulin binding domain of the plasma membrane Ca2+ pump (James et al., 1988) were synthesized, and their interaction with calmodulin was studied with circular dichroism, infrared spectroscopy, nuclear magnetic resonance, and fluorescence techniques. They corresponded to the complete calmodulin binding domain (28 residues), to its first 15 or 20 amino acids, and to its C-terminal 14 amino acids. The first three peptides interacted with calmodulin. The K value was similar to that of the intact enzyme in the 28 and 20 amino acid peptides, but increased substantially in the shorter 15 amino acid peptide. The 14 amino acid peptide corresponding to the C-terminal portion of the domain failed to bind calmodulin. 2D NMR experiments on the 20 amino acid peptides have indicated that the interaction occurred with the C-terminal half of calmodulin. A tryptophan that is conserved in most calmodulin binding domains of proteins was replaced by other amino acids, giving rise to modified peptides which had lower affinity for calmodulin. An 18 amino acid peptide corresponding to an acidic sequence immediately N-terminal to the calmodulin binding domain which is likely to be a Ca2+ binding site in the pump was also synthesized. Circular dichroism experiments have shown that it interacted with the calmodulin binding domain, supporting the suggestion (Benaim et al., 1984) that the latter, or a portion of it, may act as a natural inhibitor of the pump.

Animals↗

PubMed1990

Hemoglobin binding with haptoglobin: delineation of the haptoglobin binding site on the alpha-chain of human hemoglobin.

Previous studies from this laboratory employing a comprehensive synthetic overlapping peptide strategy showed that the alpha-chain of human hemoglobin (Hb) contains a single haptoglobin (HP) binding region residing within residues alpha 121-135. The present study describes a precise delineation of this Hp-binding site on the alpha-chain. Two overlapping peptides (alpha 111-125 and alpha 121-135) spanning this region and a panel of five peptides decreasing at the C-terminal from residue 135 by decrements of two residues (alpha 119-135, alpha 119-133, alpha 119-131, alpha 119-129, and alpha 119-127) were synthesized, purified, and characterized. Quantitative radiometric titration of 125I-labeled human HP (type 2-1) with adsorbents of each of these synthetic peptides showed that the peptide alpha 119-127 retained a Hp-binding activity equivalent to that of peptide alpha 121-135. This finding indicated that Lys-127 marked the C-terminal boundary of the binding site. Another panel of eight peptides was then synthesized, which had their C-terminus fixed at Lys-127 and increased at the N-terminus by one-residue increments from residue 122 up to residue 115 (alpha 122-127, alpha 121-127, alpha 120-127, alpha 119-127, alpha 118-127, alpha 117-127, alpha 116-127, and alpha 115-127). The binding of 125I-Hp to adsorbents of these peptides demonstrated that the N-terminal boundary of the site did not extend beyond Valine 121. It is, therefore, concluded that the Hp-binding site on the alpha-chain of human Hb comprises residues alpha 121-127.

Amino Acid Sequence↗

PubMed1990

Alpha-bungarotoxin binds to human acetylcholine receptor alpha-subunit peptide 185-199 in solution and solid phase but not to peptides 125-147 and 389-409.

The nicotinic acetylcholine receptor (AChR) of human skeletal muscle has a reducible disulfide bond near the neurotransmitter binding site in each of its alpha-subunits. By testing a panel of overlapping synthetic peptides encompassing the alpha-subunit segment 177-208 (containing cysteines 192 and 193) we found that specific binding of 125I-labelled alpha-bungarotoxin (alpha-BTx) was maximal in the region 185-199. Binding was inhibited by unlabelled alpha-BTx greater than d-tubocurarine greater than atropine greater than carbamylcholine. Peptide 193-208 did not bind alpha-BTx, whereas 177-192 retained 40% binding activity. Peptides corresponding to regions 125-147 (containing cysteines 128 and 142) and 389-409, or peptides unrelated to sequences of the AChR failed to bind alpha-BTx. No peptide bound 125I-alpha-labelled parathyroid hormone. The apparent affinity (KD) of alpha-BTx binding to immobilized peptides 181-199 and 185-199 was approximately 25 microM and 80 microM, respectively, in comparison with alpha-BTx binding to native Torpedo ACh receptor (apparent KD approximately 0.5 nM). In solution phase, both peptides effectively competed with solubilized native human AChR for binding of alpha-BTx, and peptide 185-199 showed little evidence of dissociation after 24 h. Peptides that bound alpha-BTx did so when sulfhydryls were reduced. Cysteine modification, by N-ethylmaleimide or acetamidomethylation, abolished alpha-BTx-binding activity. The data implicate the region of cysteines 192 and 193 in the binding of neurotransmitter to the human receptor.

Bungarotoxins↗

PubMed1990

Synthetic alpha-subunit peptides stimulate testosterone production in vitro by rat Leydig cells.

The glycoprotein hormones (LH, hCG, FSH, and TSH) have a common 92-amino acid alpha-subunit which is noncovalently linked to a hormone-specific beta-subunit. Synthetic peptides of the alpha-subunit have been shown to inhibit binding of [125I]iodo-hCG to rat ovarian membrane and [125I]iodo-TSH to human thyroid membrane preparations. Synthetic overlapping peptides of the alpha-subunit of hCG were prepared by solid phase techniques and tested in a standard in vitro rat Leydig cell bioassay. Three regions in the alpha-subunit (alpha 1-15, alpha 30-45, and alpha 71-85) were found to stimulate testosterone production. All three regions correlate with inhibition of hCG binding to ovarian receptors, but subtle differences exist between the binding sites and effector sites. These data indicate that the glycoprotein alpha-subunit has intrinsic bioactivity.

Amino Acid Sequence↗

PubMed1990

The antigenic structure of the human glycoprotein hormone alpha-subunit. I. Characterization of anti-alpha monoclonal antibodies.

The glycoprotein hormones CG, LH, FSH, and TSH are composed of two noncovalently linked subunits, alpha and beta. The beta-subunit confers hormone specificity, while the alpha-subunit is homologous within a species. To help in determining the antigenic structure of the common alpha-subunit, six monoclonal antibodies (mAbs) to the free or heterodimeric alpha-subunit of human (h) gonadotropic hormones have been prepared and, along with two previously isolated mAbs, have been characterized for binding specificity to alpha- and beta-subunits and the human glycoprotein hormones, CG, LH, FSH, and TSH. Each mAb was derived from hybidomas of FO myeloma cells fused with spleen cells from mice immunized with free alpha-subunit, hCG or hFSH. mAbs A101, A102, and E512 were specific for the alpha-subunit but showed the highest affinity for the intact hormone; K2.18, K94.6, E501, E502, and E511 were specific for free alpha. All of the antibodies inhibited binding of 125I-hCG to luteal membrane receptor, and 125I-labeled mAbs did not recognize hCG/receptor complex. Characterization by two-site binding assays using alpha, hCG, or hFSH as antigen revealed that all the mAbs bind to unique sites on alpha which may be overlapping, and which are modified in the intact hormone. The antigenic sites for mAbs E502, E511, and K2.18 are at least partially linear because they bind to reduced, carboxymethylated alpha.

Animals↗