Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Simultaneous infection of MDCK cells with influenza A and B viruses at an equal multiplicity of infection leads to the synthesis of the proteins of both viruses. In the population of virions the hemagglutinin of influenza B virus prevails, whereas NP proteins of both viruses are present in similar quantities. Trypsin treatment of the double-infected cells resulting in the cleavage of the hemagglutinin molecules at the cell surface allows revealing the predominance of influenza B hemagglutinin on cell surface, although both hemagglutinins are accumulated in the cells. An impairment of the hemagglutinin transport to the cell surface as a possible additional mechanism of heterotypic interference and its possible effect on the polypeptide content of the phenotypically mixed virions are discussed.
 ...
PMID:[Characteristics of virion formation during mixed infection with influenza viruses A and B]. 384 40

A highly purified preparation of low molecular weight kininogen (LMrK) was isolated from the plasminogen-free rabbit blood plasma, using chromatography on DEAE-Sepharose CL-6B, gel filtration on Ultrogel AcA 34 and Sephadex G-100 as well as gradient chromatography on a hydroxylapatite column. The yield of the 320-fold purified LMrK was 16%. Trypsin released 13-14 micrograms-eq. of bradykinin (BK) from 1 mg of LMrK or 0.85-0,95 mol of BK per mol of kininogen. Rabbit LMrK consists of one polypeptide chain of Mr 69 000 and pI 4.63. Porcine pancreatic kallikrein splits off kinin from the LMrK polypeptide chain by disrupting two peptide bonds resulting in the formation of S-S-bound two chain molecule. After reduction of the S-S bonds by dithioerithritol the latter is separated into a heavy (Mr 61 000) and light (Mr 6 800) chains. A biologically active peptide was isolated from the products of CNBr cleavage of LMrK. This peptide consists of Lys-BK elongated from the C-terminal with several amino acid residues. Rabbit LMrK closely resembles human LMrK in terms of Mr, pI and location of the kinin fragment in the protein molecule.
 ...
PMID:[Single-chain, low molecular weight kininogen in the blood plasma of rabbits: isolation and fragmentation by porcine pancreatic kallikrein]. 384 17

Glucosidase II removes the inner two alpha-linked glucose residues from freshly transferred Asn-linked oligosaccharide chains in the endoplasmic reticulum. This enzyme, whose activity could be measured by the hydrolysis of an artificial substrate (p-nitrophenyl alpha-D-glucopyranoside), was purified 240-fold from a rat liver microsome fraction by DEAE-cellulose, concanavalin A-Sepharose 4B, and hydroxylapatite chromatography. The apparent molecular weight of the active polypeptide was 123 000 as estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Glucosidase II has at least one high-mannose oligosaccharide chain that can be cleaved by endoglycosidase H. Trypsin readily cleaved the 123-kilodalton (kDa) form of glucosidase II into a fully active 73-kDa core. The pattern of this cleavage suggests a domain structure for this enzyme. We demonstrate that trypsin first removes a glycosylated 25-kDa domain to yield an apparently unglycosylated 98-kDa product which is further cleaved to yield the active 73-kDa core.
 ...
PMID:Glucosidase II, a glycoprotein of the endoplasmic reticulum membrane. Proteolytic cleavage into enzymatically active fragments. 388 64

Nature and site of membrane binding of the EDTA-extractable proteins (EEP) from calf lens fiber membranes have been studied. Reassociation of EEP to EEP-free lens fiber membranes only occurs by means of calcium, not by magnesium ions. This EEP-membrane binding is not hindered by the cytoskeleton. The proportional distribution of the EEP protein components is not altered by reattachment of EEP to the membrane. Calcium appears to be a limiting factor in the reassociation of EEP with the membrane. The total amount of reassociated EEP increases with increasing calcium concentration and may largely exceed the quantity of naturally occurring EEP in lens fiber membranes. In addition, the latter EEP-containing membranes are able to bind an additional amount of EEP in the presence of calcium. These results indicate that most of the EEP-binding sites in lens fiber membranes are not occupied by EEP. Trypsin- or Staphylococcus aureus V8 protease-treated fiber membranes retain the capacity to bind EEP in the presence of calcium. This result indicates that the small polypeptide fragment of the main intrinsic protein (MIP), which is accessible to proteolytic attack, very likely is not the membrane attachment point for EEP. It is suggested that phospholipids rather than membrane proteins are involved in the calcium-dependent binding of EEP to calf lens fiber membranes.
 ...
PMID:In vitro reassociation of EDTA-extractable proteins with calf lens fiber membranes. 392 65

Wheat germ initiation factor 3 (eIF-3) is a large (15 S) particle containing 10 subunits with molecular weights ranging from 28 000 to 116 000. Two forms of wheat germ eIF-3 which differ in ability to support polypeptide synthesis in vitro have been obtained by chromatography on carboxymethyl-Sephadex (CM-Sephadex). The less active form is not retained on CM-Sephadex in 50 mM KCl and contains lower amounts of two subunits, the 116 000-dalton polypeptide (pp116) and the 36 000-dalton polypeptide (pp36). The more active form is retained on CM-Sephadex in 50 mM KCl and is eluted by 150 mM KCl. Treatment of the more active form with small amounts of trypsin results in a rapid degradation of four of the subunits (pp116, pp107, pp87, and pp36) and in a rapid loss in the ability to support polypeptide synthesis. Trypsin treatment also diminishes the ability of eIF-3 to support the binding of mRNA to 40S ribosomal subunits. These findings indicate that pp116, pp107, pp87, and pp36 are in exposed positions in the eIF-3 particle and that pp116 and/or pp36 are essential for activity.
 ...
PMID:Characterization of initiation factor 3 from wheat germ. 1. Effects of proteolysis on activity and subunit composition. 401 79

The substructure of the tubulin molecule was studied by limited proteolysis and high affinity polyclonal antibodies specific for alpha or beta-tubulin. Brief enzymatic cleavage separates the tubulin monomer into two domains of unequal size. Trypsin splits alpha-tubulin into components with Mr values of 36 X 10(3) and 14 X 10(3), chymotrypsin splits beta-tubulin into 31 X 10(3) Mr and 20 X 10(3) Mr fragments. The cleavage occurs at Arg339 (alpha) and Tyr281 (beta), as determined by sequencing several N-terminal residues of the small domains, i.e. the small domains are the C-terminal parts of the molecules, the large ones are the N-terminal parts. There is a second cleavage site of chymotrypsin within Mr 10(3) to 2 X 10(3) of the C terminus of beta-tubulin. The fragments can be separated only under denaturing conditions. They copolymerize into microtubules and incomplete microtubule walls joined by a wall junction, forming S-shapes and hooks in cross-section. The antibodies were raised against electrophoretically purified tubulin monomers. Those produced with alpha-tubulin are directed predominantly against the large domains; they are either specific for alpha-tubulin or cross-react with the large domain of beta-tubulin. Conversely, antibodies raised against beta-tubulin are directed predominantly against the small domains (beta-specific and beta-cross-reacting fractions). Thus the antibodies discriminate not only between the tubulin chains but also between the domains generated by the proteases. The complementary antigenicity correlates well with the stability of the domains. Potential sites of antigenic determinants are located within the polypeptide chains by comparing theoretical predictions with the pattern of immunoblots. Two epitopes of the alpha-cross-reacting antibodies have been located approximately. One is very close to the C terminus (within about 20 residues), the other is close to the N terminus (within about Mr 8 X 10(3) ). The epitope of the beta-cross-reacting antibody is also located within Mr 12 X 10(3) of the C terminus. The antibodies prevent microtubule assembly and cause disassembly of preformed microtubules. A variety of breakdown products are observed by electron microscopy. They include fibres of about 10 nm width, sheets with undefined substructure, thick tapered fibrous bundles and wispy filaments.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Tubulin domains probed by limited proteolysis and subunit-specific antibodies. 405 49

Bovine photoreceptor membranes have been treated with proteases to determine the accessibility of rhodopsin to these large, water soluble molecules. The polypeptides that remain associated with the membranous structure after proteolysis were detected by sodium dodecyl sulfate gel electrophoresis. Thermolysin and chymotrypsin degraded rhodopsin (apparent mol wt 35,000-36,000) to fragments of 29,000 and 23,000 apparent mol wt, respectively, without affecting the chromophoric absorption of the molecule or removing the region of the polypeptide carrying carbohydrate. The two fragments were isolated and their amino acid compositions were determined. They do not appear to be more hydrophobic than rhodopsin. Subtilisin, at low concentration and temperature, produced a fragment with the same molecular weight as that produced by thermolysin. At higher concentrations, subtilisin yields major fragments of mol wt 23,000 and 20,000 without affecting the chromophoric absorption. Two intermediate fragments of apparent mol wt 29,000 and 26,000 were detected during the course of this degradation. Carbohydrate is retained by all but the smallest fragment. Bleaching of the photoreceptor pigment did not appreciably alter any of the fragmentation patterns. Trypsin did not alter the molecular weight of rhodopsin under the conditions of this study. Approximately 35-45% of rhodopsin appears to be accessible to the aqueous environment and can be removed without affecting the chromophoric properties of the retinaldehyde-carrying region which remains bound to the membrane.
 ...
PMID:The accessibility of bovine rhodopsin in photoreceptor membranes. 441 32

Rough microsomes were incubated in an in vitro amino acid-incorporating system for labeling the nascent polypeptide chains on the membrane-bound ribosomes. Sucrose density gradient analysis showed that ribosomes did not detach from the membranes during incorporation in vitro. Trypsin and chymotrypsin treatment of microsomes at 0 degrees led to the detachment of ribosomes from the membranes; furthermore, trypsin produced the dissociation of released, messenger RNA-free ribosomes into subunits. Electron microscopic observations indicated that the membranes remained as closed vesicles. In contrast to the situation with free polysomes, nascent chains contained in rough microsomes were extensively protected from proteolytic attach. By separating the microsomal membranes from the released subunits after proteolysis, it was found that nascent chains are split into two size classes of fragments when the ribosomes are detached. These were shown by column chromatography on Sephadex G-50 to be: (a) small (39 amino acid residues) ribosome-associated fragments and (b) a mixture of larger membrane-associated fragments excluded from the column. The small fragments correspond to the carboxy-terminal segments which are protected by the large subunits of free polysomes. The larger fragments associated with the microsomal membranes depend for their protection on membrane integrity. These fragments are completely digested if the microsomes are subjected to proteolysis in the presence of detergents. These results indicate that when the nascent polypeptides growing in the large subunits of membrane-bound ribosomes emerge from the ribosomes they enter directly into a close association with the microsomal membrane.
 ...
PMID:Controlled proteolysis of nascent polypeptides in rat liver cell fractions. II. Location of the polypeptides in rough microsomes. 545 93

The structure of the alpha 1-adrenergic receptor was investigated by comparing polypeptides identified by sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis with the size of the intact receptor in cell membranes as determined by target size analysis. The alpha 1-adrenergic receptor from rat liver membranes affinity-labeled with [3H]phenoxybenzamine, a covalent affinity reagent, appeared as a single polypeptide with a molecular mass of 85,000 daltons (Da) on NaDodSO4-polyacrylamide gels. In the absence of protease inhibitors, smaller peptides of 58-62 kDa and 40-45 kDa, specifically labeled with [3H]phenoxybenzamine, were also apparent on NaDodSO4 gels. In order to determine whether the 85-kDa protein represented all or only a portion of the alpha 1-receptor, radiation inactivation (target size analysis) was undertaken. Radiation-induced receptor inactivation was measured by the loss of specific [3H]phenoxybenzamine and [3H]prazosin binding and by the loss of affinity-labeled alpha 1-adrenergic receptors on NaDodSO4 gels. Target size analysis of rat liver alpha 1-receptors indicated that the intact membrane-bound receptor has an average molecular mass of 160,000 Da. These data suggest that the intact alpha-receptor may exist in the membrane as a dimer of two 85,000-Da subunits. The structure of the alpha 1-receptor was further studied by limited proteolysis of the 85-kDa protein isolated from NaDodSO4 gels. Trypsin, chymotrypsin, and papain produce smaller peptides similar to those produced during membrane isolation in the absence of protease inhibition. Limited proteolysis of the membrane-bound receptor produces water-soluble peptides, the largest of which is 45,000 Da. This peptide contains the ligand-binding domain and protrudes from the membrane into the extracellular space.
 ...
PMID:Alpha 1-adrenergic receptor structure. 609 Aug 81

EDP208 conjugative pili contain a single polypeptide subunit of 11,500 daltons with a blocked N-terminus. This N-terminal blocking moiety was identified as an N-acetyl group by 1H nuclear magnetic resonance analysis of an N-terminal tripeptide isolated from pronase digests of EDP208 pilin. Limited acid hydrolysis of the tripeptide allowed its sequence to be determined as acetyl-NH-Thr-Asp-Leu. Trypsin digestion of EDP208 pilin resulted in the quantitative release of a fragment containing 12 residues from the N-terminus of the protein. The sequence of this dodecapeptide was determined to be acetyl-NH-Thr-Asp-Leu-Leu-Ala-Gly-Gly-Lys-Asp-Val-Asp-Lys.
 ...
PMID:N-terminal amino acid sequencing of EDP208 conjugative pili. 613 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>