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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The contacts between bulky hydrophobic side chains (Val, Leu, Ile, Met, Phe, Tyr, and Trp) were studied in five globins with known three-dimensional structures. It is shown that a large majority of these side chains participate in such contacts, where most often one side chain makes contact with two to four nearby side chains. The "recognition element" of a helical region is most often a pair of bulky hydrophobic side chains belinging to neighboring turns of an alpha-helix. Such pairs most often make contact with bulky hydrophobic side chains brought in from the outside. An analysis is made of contacts between the hydrophobic side chains common to all five globins. It is shown that as a rule the most intense contacts in each globin are also common to the five globins. The role of these invariant contacts in the formation of the tertiary structure of globin molecules is considered. A suggestion is made that the apoglobin molecule consists of independently self-organizing halves, the internal structure of which is less subject to fluctuation than their mutual arrangement.
Mol Biol 1975 Jan
PMID:The structure of hydrophobic cores of globins. 112 3

Two series of neurohypophysial peptide amino-acylated derivatives were tested for their ability to activate plasma membrane adenylate cyclase prepared from pig or rat kidney. They were firstly [8-lysine]-vasopressin-related derivatives (Na-[Glycyl-Cys]1-[8-Lysine]-vasopressin and Na-[Glycyl-Glycyl-Cys51-[8-Lysine]-vasopressin) and secondly oxytocin-related derivatives (Na-[Glycyl-Cys-a1)-oxytocin, Na-[Leucyl-Glycyl-Glycyl--Cys]-oxytocin, and Na-[Glycyl-Cys]-[2-0methyl tyrosine]-oxtocin). The maximal adenylate cyclase activation induced by these peptides was lower than that induced by their respective parent hormones. After incubation of these analogues with plasma membranes obtained from the renal medulla, no significant release of parent hormones occurred. Good qualitative correlations were observed between relative antidiuretic activities measured in vivo and relative potencies in activating adenylate cyclase. It was concluded that direct action of peptides tested on the kidney is at least partly responsible for their antidiuretic activity in vivo.
Mol Cell Endocrinol 1975 Jan
PMID:Renal adenylate cyclase activation by amino acylated vasopressin and oxytocin. 114 16

Nucleotidyl-(5' leads to N)-amino acids containing different heterocycle bases: adenine, guanine, hypoxanthine, cytosine, uracyl, and aromatic amino acids: phenylalanine, tyrosine and tryptophan, have been investigated by proton magnetic resonance and circular dichroism. For all the compounds studied folded conformation have been shown stabilized by hydrophobic interaction in aqueous solution. The comparison of the results of the studied nucleotidyl-(5' leads to N)-amino acids unable us to build four secondary structure types in these very compounds. Phenylalanine and tyrosine derivatives of purine nucleotides can be regarded as the first type, tryptophan derivatives of purine nucleotides as the second type, phenylalanine and tyrosine derivatives of pyrimidine nucleotides as the third type and tryptophan derivatives of pyrimidine nucleotides as the fourth type. For each group of these compounds conformational models have been built. In all these compounds the anti-conformation has been proved to exist.
Mol Biol (Mosk)
PMID:[The secondary structure of nucleotidyl-(5' bound to N)-amino acids containing different heterocyclic bases and amino acids]. 121 5

Using an Cphi-4A spectrophotometer (USSR), denaturation of DNA containing approximately 2% residual protein has been studied in the presence of catecholamines and their precursors: epinephrine, beta-3,4-dioxyphenylalanine, norepinephrine, 3,4-dimethoxyphenylethylamine, tyrosine, and phenylalanine. All these substances, excluding phenylalanine, induce positive excessive hyperchromicity (as compared to initial DNA). The correlation between this effect and molecular structures of the substances studied has been shown to exist. An increase of DNA hyperchromicity in the presence of catecholamines has been found to result from the oxygen presence in the aromatic rings of the catecholamines molecules. It is assumed that the interaction between the negative O-atoms in catecholamines and bivalent metal cations in the nucleoprotein complex weakens the DNA-protein binding. This leads to an additional disorientation due to the heat of nucleic acid bases, which were previously bound by the residual protein.
Mol Biol (Mosk)
PMID:[DNA fusion in the presence of catecholamines and substances close to them in structure]. 122 65

The surface topography of the intact 70S ribosomes and free 30S and 50S subunits from Bacillus stearothermophilus strain 2184 was investigated by lactoperoxidase-catalyzed iodination. Two-dimensional polyacrylamide gel electrophoresis was employed to separate ribosomal proteins for analysis of their reactivity. Free 50S subunits incorporated about 18% more 125I than did 50S subunits derived from 70S ribosomes, whereas, free 30S subunits and 30S subunits derived from 70S ribosomes incorporated similar amounts of 125I. Iodinated 70S ribosomes and subunits retained 62-78% of the protein synthesis activity of untreated particles and sedimentation profiles showed no gross conformational changes due to iodination. The proteins most reactive to enzymatic iodination were S4, S7, S10 and Sa of the small subunit and L2, L4, L5/9, L6 and L36 of the large subunit. Proteins S2, S3, S7, S13, Sa, L5/9, L10, L11 and L24/25 were labeled substantially more in the free subunits than in the 70S ribosome. Other proteins, including S5, S9, S12, S15/16, S18 and L36 were more extensively iodinated in the 70S ribosomes than in the free subunits. The locations of tyrosine residues in some homologous ribosomal proteins from B. stearothermophilus and E. coli are compared.
Mol Gen Genet 1976 Mar 30
PMID:Surface topography of the Bacillus stearothermophilus ribosome. 127 47

Cytoplasmic aspartate aminotransferase from beef kidney loses 25% of its activity on nitration with tetranitromethane while the apoenzyme about 95%. In the holoenzyme 0.5 tyrosine residue and 1.0 tyrosine residue in the apoenzyme are nitrated per enzyme protomer. In addition 1 cysteine residue per protomer is oxidized in both. The presence of substrates, alpha-ketoglutarate and glutamate, both at ten times their Km values, does not change these results. Mercaptoethanol does not affect the residual activity of either the nitrated holo or apoenzyme. Dithionite abolishes the activity of the nitrated holoenzyme by reducing tha coenzyme moiety. It has no effect on the native holoenzyme or on either the native or nitroapoenzyme.
Mol Cell Biochem 1976 Apr 28
PMID:Role of tyrosine residues in cytoplasmic aspartate aminotransferase from beef kidney. 127 58

1. Six men were infused intravenously for 10 h with a tracer amount of L-[U-14C]tyrosine while on a standardized food intake. 2. Measurements of plasma L-[14C]-tyrosine specific radioactivity and the excretion rate of 14CO2 were made at frequent intervals and showed plateau labelling of plasma and expired carbon dioxide within 6-8 h. The tyrosine flux was calculated from the specific radioactivity in plasma at plateau value. 3. The excretion rate of 14CO2, corrected for retention of label within the bicarbonate pool, showed that oxidation accounted for 20% of the tyrosine flux. Urinary excretion of label was negligible. 4. Rates of protein synthesis were calculated from the flux of tyrosine after subtracting the proportion oxidized. Although the mean rate of synthesis was consistent with other measurements of protein turnover, the individual values ranged from 284 to 387 g/day. The variation was not reduced by relating turnover to body weight, lean body mass or energy expenditure. 5. Estimating the rates of protein breakdown from the tyrosine flux involved some assumptions about pathways of phenylalanine metabolism. The use of a labelled essential amino acid would therefore give more accurate values for short-term measurements of whole body protein turnover.
Clin Sci Mol Med 1976 Jun
PMID:Studies of amino acid and protein metabolism in normal man with L-[U-14C]tyrosine. 127 58

The RNase P cleavage reaction was studied as a function of the number of base-pairs in the acceptor-stem and/or T-stem of a natural tRNA precursor, the tRNA(Tyr)Su3 precursor. Our data suggest that the location of the Escherichia coli RNase P cleavage site does not depend merely on the lengths of the acceptor-stem and T-stem as previously suggested. Surprisingly, we find that precursors with only four base-pairs in the acceptor-stem are cleaved by M1 RNA and by holoenzyme. Furthermore, we show that both disruption of base-pairing, and alteration of the nucleotide sequence (without disruption of base-pairing) proximal to the cleavage site result in aberrant cleavage. Thus, the identity of the nucleotides near the cleavage site is important for recognition of the cleavage site rather than base-pairing. The important nucleotides are those at positions -2, -1, +1, +72, +73 and +74. We propose that the nucleotide at position +1 functions as a guiding nucleotide. These results raise the possibility that Mg2+ binding near the cleavage site is dependent on the identity of the nucleotides at these positions. In addition, we show that disruption of base-pairing in the acceptor-stem affects both Michaelis-Menten constants, Km and kcat.
J Mol Biol 1992 Oct 20
PMID:Several regions of a tRNA precursor determine the Escherichia coli RNase P cleavage site. 127 79

We have examined the effects of Xenopus pp60c-src with constitutive kinase activity on the morphology and maturation of Xenopus laevis oocytes. When RNA encoding this deregulated variant was injected into stage VI oocytes, we observed a gross alteration in the cortex of the oocyte. This alteration involved aggregation of pigment and invagination of the cortex in a large area proximal to the site of injection. This phenomenon was not seen in oocytes injected with RNA encoding wild-type pp60c-src. We have correlated this phenomenon with the tyrosine phosphorylation of 84- and 100-kDa proteins. These phosphorylated proteins colocalized with the alteration in the oocyte cortex when assayed by both biochemical and immunocytochemical methods. Neither the pigment aggregation nor phosphorylation of the 84- and 100-kDa proteins was observed in oocytes expressing a nonmyristoylated version of the deregulated pp60c-src. Expression of deregulated Xenopus fyn, a src-family member, resulted in a phenotype similar to that seen with deregulated src. However, in the fyn-injected oocytes, many more proteins were phosphorylated on tyrosine than in the src-injected oocytes. Progesterone stimulation of oocytes expressing deregulated pp60c-src resulted in an increase in the number of tyrosine-phosphorylated proteins. This change may represent the response of pp60src to the resumption of the cell cycle in maturing oocytes. These data suggest that the oocyte may be a particularly useful system for investigating the role of pp60c-src in the regulation of cytoskeletal structure and in the regulation of events associated with the cell cycle.
Mol Cell Biol 1992 Dec
PMID:Biochemical and cytological changes associated with expression of deregulated pp60src in Xenopus oocytes. 128 Mar 23

The cell surface molecule CD2 has a signaling role in the activation of T lymphocytes and natural killer cells. Because perturbation of CD2 leads to the appearance of tyrosine-phosphorylated proteins, we investigated the possibility that CD2 associates with cytoplasmic protein tyrosine kinases. As determined by in vitro kinase assays and phosphoamino acid analysis, protein tyrosine kinase activity coprecipitated with CD2 from rat T lymphocytes, T lymphoblasts, thymocytes, interleukin-2-activated natural killer cells, and RNK-16 cells (a rat natural killer cell line). In each case, both p56lck and p59fyn were identified in the CD2 immunoprecipitate. In the thymus, the association between CD2 and these kinases occurred predominately in a small subset of thymocytes that had the cell surface phenotype of mature T cells, indicating that the association is a regulated event and occurs late in T-cell ontogeny. The finding that CD2 is associated with p56lck and p59fyn in detergent lysates suggests that interactions with these Src-like protein kinases play a critical role in CD2-mediated signal transduction.
Mol Cell Biol 1992 Dec
PMID:Association of Src-like protein tyrosine kinases with the CD2 cell surface molecule in rat T lymphocytes and natural killer cells. 128 Mar 24


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