Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:Q07644 (polypeptide)
72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human choriogonadotropin (hCG) is a heterodimeric hormone consisting of an alpha subunit and a beta subunit. hCG and aglycosylated hCG (aghCG) have similar receptor binding affinities but differ in their ability to activate hormone-responsive adenylate cyclase. aghCG is an effective antagonist. The mechanisms of this antagonism and interactions of antagonistic aghCG with the receptor are not understood. To address this critical question, we have examined the interaction of this hormone analog with the receptor. The hormone receptor on porcine granulosa cells is a glycoprotein of 86 kDa and thas three domains of 24 kDa, 28 kDa, and 34 kDa, which are disulfide-linked. They undergo proteolysis, particularly when bound to the hormones, to produce three polypeptide components. These three receptor components can readily be identified through the use of affinity labeling with the hormones. Affinity labeling with an amino-specific homobifunctional reagent and subsequent cleavage indicate that hCG is cross-linked directly to the 24-kDa receptor component. In contrast, aghCG is cross-linked directly to the 34-kDa component. The peptide map of the cross-linked aghCG-34-kDa receptor component produced by papain treatment is different from the peptide map of the cross-linked complex of hCG-24-kDa component. This difference in receptor binding may be a factor determining the success or failure of signal transduction from the receptor to the effector system, guanine nucleotide-binding regulatory protein, and adenylate cyclase.
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PMID:Differential interactions of human choriogonadotropin and its antagonistic aglycosylated analog with their receptor. 234 45

A 34,000-Da protein (P34) is one of the four major soybean oil body proteins observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of isolated organic solvent-extracted oil bodies from mature seeds. P34 is processed during seedling growth to a 32,000-Da polypeptide (P32) by the removal of an amino-terminal decapeptide (Herman, E.M., Melroy, D.L., and Buckhout, T.J. (1990) Plant Physiol, in press). A soybean lambda ZAP II cDNA library constructed from RNA isolated from midmaturation seeds was screened with monoclonal antibodies directed against two different epitopes of P34. The isolated cDNA clone encoding P34 contains 1,350 base pairs terminating in a poly(A)+ tail and an open reading frame 1,137 base pairs in length. The open reading frame includes a deduced amino acid sequence which matches 23 of 25 amino-terminal amino acids determined by automated Edman degradation of P34 and P32. The cDNA predicts a mature protein of 257 amino acids and of 28,641 Da. The open reading frame extends 5' from the known amino terminus of P34 encoding a possible precursor and signal sequence segments with a combined additional 122 amino acids. Prepro-P34 is deduced to be a polypeptide of 42,714 Da, indicating that the cDNA clone apparently encodes a polypeptide of 379 amino acids. A comparison of the nucleotide and deduced amino acid sequences in the GenBank Data Bank with the sequence of P34 has shown considerable sequence similarity to the thiol proteases of the papain family. Southern blot analysis of genomic DNA indicated that the P34 gene has a low copy number.
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PMID:Molecular cloning of a protein associated with soybean seed oil bodies that is similar to thiol proteases of the papain family. 238 Jan 91

Hexon capsomers of simian adenovirus sim16 (SA7) and of human adenoviruses h5 (Ad5) and h6 (Ad6) were proteolytically digested and the resulting products studied by SDS-polyacrylamide gel electrophoresis and by radioimmunoprecipitation analysis. The trypsinolysis of native SA7 hexon leads to a stable molecular "core" containing 4-5 fragment species of 10 to 65 kDa and resembling the intact capsomer in quarternary structure (trimer). Similar cores but consisting of smaller fragments (less than 40 kDa) were obtained after chymotryptic digestion of native SA7, Ad5 and Ad6 hexons. The chymotryptic hexon fragments were also held together in pseudotrimeric structures. The similarity of proteolytic hexon fragment patterns between different primate adenoviral hexons suggested a homology to exist in localisation of the exposed tryptic and chymotryptic cleavage sites in their respective hexon polypeptide chains. Papain caused a complete hydrolysis of native SA7 hexon (trimer) yielding small peptides, but at first stage of digestion a stable papain hexon core containing small fragments (less than 10 kDa) was observed. The tryptic SA7 hexon cores in native state retained their antigenicity in reactions with homo- and heterologous antibodies, but after core denaturation the resulting fragments had no antigenic activity of native capsomer. In contrast to the data previously published, chymotryptic cores of SA7, Ad5 and Ad6 hexons not only reacted with respective homologous antibodies but also retained (at least in part) cross-reactive antigenic determinants. The questions of formation and stability of native adenoviral hexon conformation are discussed as well as the possible nature of hexon antigenic determinants.
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PMID:[Structural and immunochemical analysis of the products of proteolysis of simian adenovirus hexons]. 241 6

The binding domains of 28 monoclonal antibodies (mAbs) against the alpha, beta, and delta subunits of the Torpedo acetylcholine receptor were mapped on the primary sequences of these subunits. Small peptide fragments (2000-20,000 daltons) of the purified subunits were obtained by digestion with staphylococcal V8 protease and papain, separated on a discontinuous polyacrylamide gel electrophoretic system, and electroblotted onto diaminophenyl thioether paper. The blots were probed with the various monoclonal antibodies and also with antibodies against carboxy-terminal decapeptides of the alpha, beta, and delta subunits to identify the carboxy-terminal fragments. From inspection of the binding patterns of the various antibodies to the subunits fragments and the molecular weights of these fragments, and by using the carboxy termini of the subunits as reference points, it was possible to deduce the regions on the primary sequence of each subunit in which the antibodies bound and in some cases to order the binding sites within these sequences. mAb 148, which inhibits receptor function by cross-linking receptor molecules on the cytoplasmic side, was mapped to the sequence beta 368-406. The main immunogenic region of the native receptor, which is of pathological importance in the autoimmune disease myasthenia gravis, was mapped by using mAb 210 to within 80 amino acid residues (alpha 46-127). The overall antigenic structure of alpha subunits was examined. Synthetic peptides have been used to locate determinants responsible for 83% of the antibodies in antisera to denatured alpha subunits and 46% of the antibodies to denatured alpha subunits in antisera to intact receptor. Theoretical models of the transmembrane orientation of the subunit polypeptide chains were tested by determining whether mapped monoclonal antibodies bound to the extracellular or intracellular surface of receptor-rich membranes. Our results confirm previous reports that the carboxy termini of the subunits are exposed on the intracellular surface, as is part of the region between a putative channel-forming domain (M5) and a putative membrane-spanning region (M3). However, contrary to current theoretical models, the region between M5 and the putative membrane-spanning sequence M4 also appears to be on the intracellular surface, implying that M4 and M5 are not membrane-spanning domains.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Location of antigenic determinants on primary sequences of subunits of nicotinic acetylcholine receptor by peptide mapping. 242 98

In inside-out red cell membrane vesicles active calcium transport and the formation of the enzyme-phosphate complex (EP) of the calcium pump were simultaneously investigated and the effects of a limited proteolytic digestion examined. In order to visualize the proteolyzed EP forms we have induced the formation of a maximum level EP from [gamma-32P]ATP in the presence of Ca2+ + La3+ and applied a good-resolution acidic discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoresis system. Proteolysis of inside-out vesicle membranes by trypsin, Pronase, papain, or chymotrypsin produces a calmodulin-like activation of the calcium pump, abolishes its calmodulin sensitivity, and decreases the original 140-kDa EP complex to a limit polypeptide of 80 kDa. Trypsin digestion produces another major intermediary fragment of 90 kDa, which is still a low-activity calmodulin-sensitive form of the pump. The red cell calcium pump is activated by trypsin both in the absence and presence of Ca2+ during digestion although the rate of activation and the appearance of the 80-kDa polypeptide are enhanced by Ca2+. If proteolytic digestion is carried out by chymotrypsin, a calmodulin-insensitive maximum activation of the calcium pump coincides with the formation of a 125-130-kDa EP-forming polypeptide. Chymotrypsin and carboxypeptidase A have synergistic effects on the formation of this latter high-activity species. Based on these data we suggest a probable molecular arrangement for the functional parts of the red cell membrane calcium pump.
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PMID:Molecular characterization of the in situ red cell membrane calcium pump by limited proteolysis. 242 14

Digestion of methylamine-treated alpha 2-macroglobulin (alpha 2M X MA) with catalytic amounts of papain at pH 4.5 has been investigated. Cleavage of Lys(1313)-Glu resulted in two major products, which could be separated by gel chromatography: a large disulfide bridged fragment set nearly the size of intact alpha 2M X MA, and an 18 kDa fragment, constituting the carboxy-terminal domain of alpha 2M. This domain contained the receptor recognition site, exposed as a result of cleavage of the internal beta-cysteinyl-gamma-glutamyl thiol esters in alpha 2M. Compared with alpha 2M-trypsin complex the apparent affinity for binding to rat hepatocyte receptors was 0.1 and 2% at 4 and 37 degrees C, respectively. The receptor-binding domain presumably forms a compact globular beta-barrel-type structure, stable at pH 2.5-9.0. Chemical modification experiments suggest that receptor binding is contributed by a determinant formed by the precise folding of the polypeptide chain.
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PMID:Domain structure of human alpha 2-macroglobulin. Characterization of a receptor-binding domain obtained by digestion with papain. 242 62

Hexon capsomers of human adenovirus type 1 (h1) labeled by iodine 125 were digested in a native state (trimers) by trypsin, chymotrypsin or papain, and the resulting hydrolysates were analyzed by SDS-PAGE. In each case, a discrete and temporally stable pattern of relatively large fragments was revealed. The degree of hexon polypeptide hydrolysis was maximal for papain, intermediate for chymotrypsin and minimal for trypsin, the largest fragments in the digest being 32, 40 and 80 kD, respectively. At room temperature, all the electrophoretically discernible hexon proteolytical fragments were held together in structures resembling intact hexon trimers and could be regarded as "hexon cores", of which papain hexon cores were the most stable during SDS-PAGE. Radioimmunoprecipitation analysis revealed a complete absence of native hexon antigenicity in thermodenaturated fragments of hexon protease digests, while native trypsin, chymotrypsin and papain hexon cores could be precipitated by hexon-specific antibodies. The immunoprecipitated material contained all of the hexon fragments found in appropriate hexon cores and retained the structure of the original cores. Trypsin, chymotrypsin and papain hexon cores were shown to possess at least part of native Ad h1 hexon antigenic determinants of each of the following specificities: species-specific (epsilon), cross-reactive with hexon of human adenoviruses (h3 and h6), simian adenovirus (sim 16), bovine adenoviruses (bos 3 and bos 7) and avian adenovirus (Aviadenovirus gal 1 or CELO). Thus, the full spectrum of known hexon antigenic determinants (species-specific to intergenus-crossreactive) is at least portly stable against protease attack of native hexon capsomers.
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PMID:[Stability of the structure and antigenic determinants of adenovirus type 1 native hexon to proteases]. 242 9

Macroscopic Na currents were recorded from N18 neuroblastoma cells by the whole-cell voltage-clamp technique. Inactivation of the Na currents was removed by intracellular application of proteolytic enzymes, trypsin, alpha-chymotrypsin, papain, or ficin, or bath application of N-bromoacetamide. Unlike what has been reported in squid giant axons and frog skeletal muscle fibers, these treatments often increased Na currents at all test pulse potentials. In addition, removal of inactivation gating shifted the midpoint of the peak Na conductance-voltage curve in the negative direction by 26 mV on average and greatly prolonged the rising phase of Na currents for small depolarizations. Polypeptide toxins from Leiurus quinquestriatus scorpion and Goniopora coral, which slow inactivation in adult nerve and muscle cells, also increase the peak Na conductance and shift the peak conductance curve in the negative direction by 7-10 mV in neuroblastoma cells. Control experiments argue against ascribing the shifts to series resistance artifacts or to spontaneous changes of the voltage dependence of Na channel kinetics. The negative shift of the peak conductance curve, the increase of peak Na currents, and the prolongation of the rise at small depolarization after removal of inactivation are consistent with gating kinetic models for neuroblastoma cell Na channels, where inactivation follows nearly irreversible activation with a relatively high, voltage-independent rate constant and Na channels open only once in a depolarization. As the same kind of experiment does not give apparent shifting of activation and prolongation of the rising phase of Na currents in adult axon and muscle membranes, the Na channels of these other membranes probably open more than once in a depolarization.
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PMID:Gating of Na channels. Inactivation modifiers discriminate among models. 243 40

Seven monoclonal antibodies (MAbs) reacting with high-molecular-mass components (greater than 20,000 kDa) isolated from an ovarian mucinous cyst of an A Le(a-b+) patient are described. By the use of immunoradiometric methods, these MAbs characterized seven different epitopes associated with components having a density of 1.45 g/ml by CsCl-density-gradient ultracentrifugation, like mucins. Two MAbs reacted with A and Lewis blood-group antigens respectively (polysaccharide epitopes). The five other MAbs characterized five M1 epitopes (called a, b, c, d and e), mainly associated with components of more than 20,000 kDa and 2000 kDa. They were completely destroyed by papain and 2-mercaptoethanol treatment (polypeptide epitopes). Moreover, timed trypsin digestion of native mucin resulted in a progressive loss of M1 activity and degraded these mucins into smaller M1-positive fragments. The a and c epitopes were partially degraded from relatively high-molecular-mass fragments (2000 kDa to 500 kDa) into a 100 kDa fragment. The b and d epitopes were completely degraded into smaller fragments ranging from 100 kDa to 40 kDa. The e epitope was completely destroyed by trypsin. These different pathways of M1 antigen degradation suggest the occurrence of different epitopes located in separate regions of the mucin molecules.
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PMID:Immunochemical characterization of mucins. Polypeptide (M1) and polysaccharide (A and Leb) antigens. 246 87

The sodium- and chloride-coupled gamma-aminobutyric transporter, an 80-kDa glycoprotein, has been subjected to deglycosylation and limited proteolysis. The treatment of the 80-kDa band with endoglycosidase F results in its disappearance and reveals the presence of a polypeptide with an apparent molecular mass of about 60 kDa, which is devoid of 125I-labeled wheat germ agglutinin binding activity but is nevertheless recognized by the antibodies against the 80-kDa band. Upon limited proteolysis with papain or Pronase, the 80-kDa band was degraded to one with an apparent molecular mass of about 60 kDa. This polypeptide still contains the 125I-labeled wheat germ agglutinin binding activity but is not recognized by the antibody. The effect of proteolysis on function was examined. The transporter was purified by use of all steps except that for the lectin chromatography [Radian, R., Bendahan, A., & Kanner, B.I. (1986) J. Biol. Chem. 261, 15437-15441]. After papain treatment and lectin chromatography, gamma-aminobutyric transport activity was eluted with N-acetylglucosamine. The characteristics of transport were the same as those of the pure transporter, but the preparation contained instead of the 80-kDa polypeptide two fragments of about 66 and 60 kDa. The ability of the anti-80-kDa antibody to recognize these fragments was relatively low. The observations indicate that the transporter contains exposed domains which are not important for function.
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PMID:Structural and functional studies on the sodium- and chloride-coupled gamma-aminobutyric acid transporter: deglycosylation and limited proteolysis. 250 69


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