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 capablity of ribosomes of four types of streptomycin-resistant mutants (A1, A2, A40 and A60) for non-enzymatic (EF-G--GTP-independent) translocation was tested. It was found that an A40 type mutation (amino acid replacement in position 87 of the protein S12 polypeptide chain) leads to activation of the capablity of the ribosome to perform spontaneous non-enzymatic translocation, while type A1, A2 and A60 mutations (amino acid replacements in position 42 of protein S12) does not give such an effect. Thus, it is shown that non-enzymatic translocation can be activated not only by the earlier described damage of the protein S12 by para-chloromercuribenzoate or by the complete removal of protein S12, but also by a definate mutational alteration of the protein. Preliminary data are also reported on the possibility of activating non-enzymatic translocation by combinations of mutational alterations of the ribosomal proteins other than protein S12 but interdepending with it (such as S4 and S5).
Mol Gen Genet 1975 Jul 10
PMID:Non-enzymatic translocation in ribosomes from streptomycin-resistant mutants of Escherichia coli. 109 89

Nine sucrose nonfermenting mutants have been isolated from yeast strain EK-6B, carrying the tightly linked SUC3 and MAL3 genes. These mutants are allelic to the SUC3 gene recessive in nature and none of them has detectable levels of either internal or external invertase. A single point mutation leading to the loss of both invertases suggests that either SUC3 is a control gene or codes for a polypeptide which is shared by both invertases.
Mol Gen Genet 1975 Oct 22
PMID:Genetic control of invertase formation in Saccharomyces cerevisiae. I. Isolation and characterization of mutants affecting sucrose utilization. 110 7

Plasma glycoprotein synthesis in the liver occurs in a stepwise fashion. The first sugar, N-acetyl-glucosamine, is attached to the protein during the growth of the polypeptide chain on the membrane-bound ribosomes. Subsequent carbohydrates are incorporated after the completion of the protein in the lumen of the endoplasmic reticulum and Golgi apparatus. The reactions are carried out by enzymes strongly bound to the membranes. Because the glycosylation reaction occurs in the interior of the cytoplasmic tubules a permeability problem for the nucleotide sugar exists. Recent studies indicate that sugar-lipids are formed on the cytoplasmic site of the membrane and these complexes transfer the sugars across the membrane. Experimental evidence for this pathway is presented in this article.
Mol Cell Biochem 1975 Jan 31
PMID:A proposed pathway of plasma glycoprotein synthesis. 112 82

X-ray scattering curves for the sperm whale myoglobin molecule and a model which includes only the helical regions of the polypeptide chain are calculated. The portion of the scattering curve associated with the packing of the helices inside the protein globule is analyzed. The model of the myoglobin molecule is used to investigate the sensitivity of the scattering curve to changes in the mutual packing of the helical regions.
Mol Biol 1975 Jan
PMID:Diffuse scattering of x rays by polypeptides and proteins in solution. III. Analysis of scattering curve of sperm whale myoglobin. 112 10

Avian- and mammalian-haemoglobin synthesis show different sensitivities to elevated temperatures. Temperature-dependent, reversible polyribosome disaggregation in avian cells occurs only at 45 degrees C, which is 3 degrees higher than the temperature for mammalian cells, and seems to be due to a block in the initiation of new polypeptide chains. The implications of these findings are discussed.
Mol Biol Rep 1975 Mar
PMID:Different sensitivities of avian- and mammalian-haemoglobin synthesis to elevated temperatures. 112 16

The antibody response of genetically inbred rats to poly(Glu52Lys33Tyr15) is controlled by a complex polygenic system which includes at least two autosomal genes and a sex influence, which may also be genetically determined. The genetic control of the quantity, binding constants, and specificity of the antibody formed linked to the major histocompatibility locus. Factors other than the major genetic ones and the sex influence also affect the quantity of antibody formed, since animals of the same genotype can make significantly different amounts of antibody, depending upon the crosses by which they acquire the major histocompatibility alleles. After immunization with poly(Glu52Lys33Tyr15) the low responders make fewer antibody-producing cells, are not capable of mounting a delayed hypersensitivity reaction to the polypeptide and appear to be deficient in their ability to produce the specific IgM antibody. Immunization of the low responders with antigen aggregated with methylated bovine serum albumin enhances the quantity of antibody formed, increases the binding constants and crossreactivity of the antibody and enhances the delayed hypersensitivity response. In contrast to the findings with the L-amino acid polypeptide, there does not appear to be any genetic control over the antibody response to the D-amino acid enantiomorph poly(DGlu52DLys33DTyr15), which is minimal in all strains.
Mol Cell Biochem 1975 Jun 30
PMID:The genetic control of the antibody response in inbred rats. 115 44

Host Factor (HF)1, is a 12000 molecular weight polypeptide that is found in uninfected Escherichia coli and is required as a hexamer along with Qbeta replicase for in vitro replication of Qbeta phage RNA. It has recently been found to be associated with ribosomes and to bind tightly to poly(A). We report here the identification and purification of HF from Pseudomonas putida. HF can be detected in crude extracts by both functional activity in the Qbeta RNA replication assay and by immunodiffusion with antibody made against E. coli HF. HF from E. coli and P. putida chromatograph similarly on DEAE-cellulose and phosphocellulose. They have similar but not identical molecular weights as judged by SES-polyacrylamide gel electrophoresis. Like E. coli HF, P. putida HF was found to be associated with ribosomes and to bind tightly to poly(A). Furthermore, the pure protein from P. putida has full funcitonal activity in the in vitro Qbeta RNA replication assay. The findings that HF has been conserved during evolution, is associated with ribosomes, and binds poly(A), suggest that HF may be an important translational element in uninfected cells and that its role involves an interaction with RNA.
Mol Gen Genet 1975 Nov 24
PMID:Host factor for coliphage Qbeta RNA replication is present in Pseudomonas putida. 120 67

The polypeptide composition of Fraction I protein from Nicotiana digluta, a synthetic species which arose by chromosome doubling following the interspecific hybridization of N. glutinosa and N. tabacum, has been examined by isoelectric focusing. The composition of the protein from N. digluta, which was identical to the protein from the infertile F1 hybrid N. glutinosa x N. tabacum, showed 3 polypeptides in the large subunit and 4 polypeptides in the small subunit. The large subunit polypeptides were identical to those from N. glutinosa, the maternal parent in the original hybridization, whereas the small subunit polypeptides were a composite of the small subunit polypeptides from both N. glutinosa and N. tabacum. This analysis demonstrates how the polypeptide composition of Fraction I protein evolves during the origin of new species of Nicotiana.
J Mol Evol 1975 Dec 31
PMID:The evolution of fraction i protein during the origin of a new species of Nicotiana. 121 6

A model is proposed for the structure of stereospecific sites in regulatory proteins. On its basis a possible code is suggested that governs the binding of regulatory proteins at specific control sites on DNA. Stereospecific sites of regulatory proteins are assumed to contain pairs of antiparallel polypeptide chain segments which form a right-hand twisted antiparallel beta-sheet, with single-stranded regions at the ends of the beta-structure. The model predicts that binding reaction between a regulatory protein and double-helical DNA is a cooperative phenomenon and is accompanied by significant structural alteration at the stereospecific site of the protein. Half of hydrogen bonds normally existing in beta-structure are broken upon complex formation with DNA and a new set of hydrogen bonds is formed between polypeptide amide groups and DNA base pairs. In a stereospecific site, one chain (t-chain) is attached through hydrogen bonds to the carbonyl oxygens of pyramides and N3 adenines lying in one DNA strand, while the second polypeptide chain (g chain) is hydrogen bonded to the 2-amino groups of guanine residues lying in the opposite DNA strand. The amide groups serve as specific reaction sites being hydrogen bond acceptors in g-chain and hydrogen bond donors in t-chain. The single-stranded portions of t- and g-chains lying in neighbouring subunits of regulatory protein interact with each other forming deformed beta-sheets. The recognition of regulatory sequences by proteins is based on the structural complementarity between stereospecific sites of regulatory proteins and base pairs sequences at the control sites. An essential feature of these sequences is the asymmetrical distribution of guanine residues between the two DNA strands. The code predicts that there are six fundamental amino acid residues (serine, threonine, asparagine, histidine, glutamine and cysteine) whose sequence in stereospecific site determines the base pair sequence to which a given regulatory protein would bind preferentially. The code states a correspondence between four amino acid residues at the stereospecific site of regulatory protein with the two residues being in t- and g-segments, respectively, and AT(GC) base pair at the control site. It is thus possible to determine which amino acid residues in the repressor and which base pairs in the operator DNA are involved in specific interactions with each other, as exemplified by lac repressor binding to lac operator.
Mol Biol (Mosk)
PMID:[A code governing specific binding of regulatory proteins to DNA and structure of stereospecific sites of regulatory proteins]. 121 4

An assumption is made on the substantial role of local hydrogen bonds in formation of irregular regions of globular protein polypeptide chains. The statistics of the amino acid composition of irregular regions is examined from this point of view. A statistical analysis of side group-backbone hydrogen bonds is carried out for three proteins: alpha-chy-motrypsin, lysozyme and myoglobin. It is shown that short side groups participate in formation of local hydrogen bonds more often than long ones. Conformations of amino acid residues in the first and the last positions are studied in beta-bends of 9 proteins. It is shown that over 70% of these residues are in conformations corresponding to the formation of local hydrogen bonds of three types: backbone-backbone, side groupbackbone, backbone-water molecule-backbone. Thus, the participation of the cooperative hydrogen-bonding network in stabilization of beta-bends is demonstrated.
Mol Biol (Mosk)
PMID:[The role of local hydrogen bonds in formation of irregular regions of globular protein polypeptide chains]. 121 11


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