Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The structural components of antigen molecules that interact with class II major histocompability complex (MHC) molecules on antigen-presenting cells (APCs) (agretopes) and with antigen receptors of T-lymphocytes (epitopes) in class II restricted T-cell responses have not been precisely defined. This issue was addressed here using murine T-cell clones specific for the simple immunogen L-tyrosine-p-azobenzenearsonate (ABA-tyr) and a series of analogs of the homologous antigen. Two experimental approaches were used. First, APCs were pulsed with analogs and used to stimulate T-cell proliferation. The patterns of stimulation segregated the clones into two specificity groups and indicated that the epitope recognized by the T-cell included the arsonate group and elements in the side chain of tyrosine. Furthermore, the clones manifest different sensitivities to antigen. Second, non-stimulatory analogs were used to block the presentation of ABA-tyr in an effort to define the agretope. Compounds containing the azophenyl group blocked presentation of ABA-tyr in a dose-dependent fashion, whereas p-arsanilic acid and L-tyrosine were ineffective. The blocking was specific inasmuch as the compounds had no effect on the antigen-induced proliferative responses of giant keyhole limpet hemocyanin (KLH) or hen egg white lysozyme (HEL)-reactive T-cell clones. The blocking pattern indicated that the feature required for productive association with the APC centered on the planar structure of the azo-linked aromatic rings, with little or no contribution from either the arsonate moiety or the tyrosyl side chain. We propose that this structure forms an agretope for this family of compounds.
Mol Immunol 1984 Oct
PMID:The anatomy of an antigen molecule: functional subregions of L-tyrosine-p-azobenzenearsonate. 620 67

The uptake of L-tyrosine into wild type and antibiotic resistant strains of Schizosaccharomyces pombe requires an energy source, is initially linear with respect to time, is inhibited by 2,4-dinitrophenol and sodium azide and is saturable. However the initial uptake rates and the amount of L-tyrosine accummulated by antibiotic resistant strains are much less than wild type. Comparison of the kinetic constants of uptake shows that mutant strains have a reduced maximum velocity of uptake compared to wild type and a larger Km. Since the three mutant strains possess a permeability barrier to L-tyrosine as well as being drug resistant this is an indication that antibiotic resistance may be caused by a decrease in plasma membrane permeability.
Mol Gen Genet 1982
PMID:Multiple drug resistance in the fission yeast Schizosaccharomyces pombe: evidence for the existence of pleiotropic mutations affecting dependent transport systems. 695 8

We have investigated the microheterogeneity of hybridoma products (HP) expressing the major idiotype (CRIA) associated with A/J antibodies to the p-azophenylarsonate (Ar) hapten group. The properties investigated were affinity for a phenylarsonate derivative and the fine specificity of the combining sites of the various HP. The fine specificity was approached by measuring relative affinities for a series of related haptens. It was found that, although variations exist, there are strong similarities in affinities and fine specificities of the antigen-binding sites of CRI+A HP. The range of affinities for (p-azobenzenearsonic acid)-N-3H-acetyl-L-tyrosine was 0.41 x 10(6)-2.2 x 10(6) M-1. In all cases the addition of a second ring structure (benzene or histidine) and an azo group greatly increased the binding affinity. Some differences in fine specificity among the HP were seen with respect to affinities for o-arsanilate or the arsanilate derivative of histidine. However, the two HP which are the strongest inhibitors in the conventional assay for CRIA were virtually identical to one another and to induced A/J anti-Ar antibodies in their fine specificities. Together with previous data on amino acid sequences and serological properties, the results indicate that, despite their microheterogeneity, members of the CRIA family are closely related in structure and hapten-binding specificity.
Mol Immunol 1982 Nov
PMID:Degree of heterogeneity of binding specificities of antibodies to the phenylarsonate group that share a common idiotype. 718 11

Semi-empirical calculations of conformational properties of acetyl-L-tyrosine, glycyl-L-tyrosine, acetyl-L-alanyl-L-tyrosine and acetyl-L-alanyl-L-alanyl-tyrosine and their noncovalent complexes with carboxypeptidase A (CPA) are presented. Each of these molecules binds in the active site of CPA by only one binding mode. The substrates are practically free of intramolecular tension. It is shown that the binding of an aromatic side chain of a C-terminal residue of substrate provides productive orientation of the susceptible peptide bond. The sterochemical aspects of the interactions of Tyr-248 and Glu-270 residues with the substrates are considered.
Mol Biol (Mosk)
PMID:[Theoretical conformational analysis of noinvalent carboxypeptidase A complexes with inhibitors and substrates]. 742 20

Biocatalytic transformations in reversed micelles formed by anionic surfactant Aerosol OT in octane have been studied at high pressures by an example of alpha-chymotrypsin-catalyzed hydrolysis of N-carbobenzoxy-L-tyrosine p-nitrophenyl ester and N-succinyl-L-phenylalanine p-nitroanilide. For the first time it has been found that the enzyme retains high activity in these water-in-oil microemulsions up to a pressure of 2 kbar. The value of the activation volume (delta V*) for the enzyme reactions shows a dependence on the water content in the system. When the size of the micellar aqueous inner cavity (as evaluated at 1 atm) approaches the molecular size of alpha-chymotrypsin, delta V* becomes significantly different from the value in aqueous solution and in the micelles with a larger size. Possibilities of regulating the enzyme activity by pressure in systems with a low content of water are discussed.
Biochem Mol Biol Int 1994 Aug
PMID:Pressure effects on enzyme reactions in mainly organic media: alpha-chymotrypsin in reversed micelles of Aerosol OT in octane. 753 34

The present study was conducted to investigate the molecular identities, nature of interaction, and tyrosine phosphorylation activity of the sperm-zona pellucida binding proteins in humans. Sperm proteins belonging to four major molecular regions, namely 95, 63, 51, and 14-18 kDa, reacted with zona pellucida proteins in the Western blot and immunoprecipitation procedures. In these procedures, zona pellucida protein that reacted strongest with the sperm proteins belonged to the molecular region of 55 kDa (ZP3), besides weakly reacting proteins in the 110-kDa (ZP1/ZP2) and 14-18-kDa molecular regions. The major forces involved in the sperm-zona protein interactions were of hydrophobic and ionic in nature. Three (95, 51, and 14-18 kDa) of the four molecular regions of sperm proteins that bound to the zona pellucida proteins also seem to involve o-phospho-L-tyrosine residues in their interaction, and these proteins demonstrated the presence of phosphotyrosine residues, and the 51-kDa protein also showed autophosphorylating activity in the in vitro kinase assay. The sperm binding zona protein of 55 kDa also demonstrated autophosphorylating activity. Using specific monoclonal antibody to the well characterized sperm-specific glycoprotein, designated FA-1, and the competitive inhibition in the immunoprecipitation procedure, it was found that the 51 kDa protein is indeed FA-1 antigen. Besides elucidating the molecular nature of the sperm-zona interaction, these antigens will find application in the development of a multivalent contraceptive vaccine, and may also help in specific diagnosis and treatment of infertility mediated through defective gamete (sperm or oocyte) function.
Mol Reprod Dev 1994 Dec
PMID:Molecular identities of human sperm proteins that bind human zona pellucida: nature of sperm-zona interaction, tyrosine kinase activity, and involvement of FA-1. 753 65

This work studies the phenotype changes, relating to pigment expression, of a human melanoma cell line. The phenotypic instabilities and proliferation rates are correlated with the production and release in the cell culture medium of active oxygen species and melanin synthesis intermediates. The proliferation rates versus L-tyrosine concentration in the culture media are investigated: a decrease is found when high L-tyrosine is added to the medium. This would be consistent with the release of cytotoxic and/or genotoxic species by melanoma cells. The morphology of melanoma melanosomes is coherent with the leakage of cytotoxic and genotoxic species produced during melanin synthesis.
Biochem Mol Biol Int 1994 Apr
PMID:Cyto-genotoxic species leakage within human melanoma melanosomes. Molecular-morphological correlations. 806 41

An enzyme fraction with catalytic activities for the biosynthesis of the pipecolic acid containing cyclopeptolide SDZ 90-215 was partially purified and characterized from the genus Septoria. The crude cell homogenate was subjected to polyethyleneimine precipitation, ammonium sulfate precipitation and FPLC gel filtration. The denatured enzyme shows an apparent molecular mass of 1.2 MDa in 3% SDS-PAGE. Peptolide SDZ 90-215 synthetase catalyzes the ATP-PPi exchange reaction dependent on all substituent amino and hydroxy acids. SDZ 90-215 synthetase synthesizes the peptolide in vitro when incubated together with D-lactic acid, all constitutive amino acids in their N-unmethylated form, ATP, magnesium chloride and S-adenosyl-L-methionine. The yield of SDZ 90-215 is higher when O-methyl-L-tyrosine instead of L-tyrosine is used, indicating that O-methylation of tyrosine is not carried out by the synthetase.
Biochem Mol Biol Int 1993 Dec
PMID:In vitro biosynthesis of peptolide SDZ 90-215 by a 1.2 MDa multienzyme polypeptide. 813 97

We postulate that in mammalian systems neurotransmitter and hormone-like functions of L-tyrosine (LT) and L-DOPA (LD) are mediated via specific membrane-bound and/or nuclear receptors. The structure and function of these receptors may represent an evolutionary continuum of regulatory proteins binding LT or LD in unicellular and lower multicellular organisms.
Mol Cell Endocrinol 1994 Mar
PMID:Towards defining receptors for L-tyrosine and L-dopa. 820 17

Tyrosine hydroxylase (TH) catalyzes the conversion of L-tyrosine to L-dihydroxyphenylalanine (L-DOPA), the rate-limiting step in the biosynthesis of dopamine. Recently, we described a point mutation in hTH (Q381K) in a family of two siblings suffering from progressive L-DOPA-responsive dystonia (DRD), representing the first reported mutation in this gene. We here describe the cloning, expression and steady-state kinetic properties of the recombinant mutant enzyme. When expressed by a coupled in vitro transcription-translation system and in E. coli, the mutant enzyme represents a kinetic variant form, with a reduced affinity for L-tyrosine. The 'residual activity' of about 15% of the corresponding wild-type hTH (isoform hTH1), at substrate concentrations prevailing in vivo, is compatible with the clinical phenotype of the two Q381K homozygote patients carrying this recessively inherited mutation.
Hum Mol Genet 1995 Jul
PMID:Recessively inherited L-DOPA-responsive dystonia caused by a point mutation (Q381K) in the tyrosine hydroxylase gene. 852 10


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