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81.
Evolution of epitopes on human and nonhuman primate lymphocyte cell surface antigens 总被引:4,自引:0,他引:4
Edward A. Clark Paul J. Martin John A. Hansen Jeffrey A. Ledbetter 《Immunogenetics》1983,18(6):599-615
The T- and B-cell surface polypeptides detected by an international workshop panel of 100 mouse monoclonal antibodies (M.Ab) were biochemically defined by radioimmunoprecipitation. Eight T-cell-associated molecules and eight B-cell-associated molecules were identified by multiple antibodies in the panel. Clusters of antibodies specific for the same polypeptide were then compared for their reactivity against peripheral blood mononuclear cells (PBMC) from 11 nonhuman primate species. All the major T- and B-cell antigens present in humans were also expressed in some nonhuman primates. M.Ab to the same antigen were found to react with distinct epitope groups that differed in their phylogenetic distribution. Some epitopes were highly conserved, while other epitopes on the same molecule were only expressed in hominoids and were not detected in old world and new world monkeys. Our detailed analysis of the phylogeny of 37 T-cell antigen epitopes on ten different molecules revealed there was no clear correspondence between the number of epitopes shared and evolutionary distance. Rather the data suggest that parallelism with back mutation may be a common mechanism in the evolution of T-cell antigens. The data also show that the tissue distribution of T-cell antigens can differ between primate species; for example, M.Ab to human Tp45 Tla-Qa-like antigens that did not react with human PBMC did react with PBMC from new world monkeys. 相似文献
82.
We have compared the partial nucleotide and derived amino acid sequences of a phaseolin seed storage protein gene ofPhaseolus vulgaris (1) and a conglycinin storage protein gene ofGlycine max (2). Although these proteins are not antigenically related to one another, the architecture of the genes is similar throughout the sequences compared here. Intervening sequences interrupt the same amino acid positions in both genes. Within the 28% of theG. max gene and the 38% of theP. vulgaris gene represented in this comparison, 73% of the nucleotides in the coding and intervening sequences are identical, excluding the insertions and deletions. The nucleotide mismatches found in the coding sequences are distributed throughout the three codon positions with little bias towards the third codon position. In addition to the single nucleotide differences, six insertions or deletions, ranging from three to twenty-seven nucleotides in length, occur in this portion of the coding region and these are partially responsible for the molecular weight differences of the conglycinin α′-subunit and the phaseolin subunit. 相似文献
83.
84.
Donald C. Morizot Jeffrey A. Greenspan Michael J. Siciliano 《Biochemical genetics》1983,21(9-10):1041-1049
Electrophoretic variation ascribable to three protein-coding loci, coding for glutamine synthetase (GS), uridine monophosphate kinase (UMPK), and transferrin (Tf), was observed in three species of fish of the genus Xiphophorus. Electrophoretic patterns in interspecific F1 hybrid heterozygotes suggested monomeric subunit structures of UMPK and Tf and a multimeric structure of undetermined subunit number of GS. Linkage analyses in backcross hybrids indicated a recombination map of GS-0%-Tf-10.8%-UMPK. This group (designated Xiphophorus linkage group VI) was shown to assort independently from the 14 enzyme loci assigned to linkage groups I-V and from 19 other informative markers within the limits of the data. 相似文献
85.
86.
87.
Jeffrey R. Bloomquist David M. Soderlund Douglas C. Knipple 《Archives of insect biochemistry and physiology》1989,10(4):293-302
Resistance to pyrethroid insecticides and dichlorodiphenyltrichloroethane (DDT) was investigated in the napts (no action potential, temperature sensitive) mutant of Drosophila melanogaster. In surface contact bioassays, the napts strain showed threefold resistance to deltamethrin at the LC50 level when compared to susceptible Canton-S flies. Cross-resistance was also observed to DDT and the pyrethroids NRDC 157 [3-phenoxybenzyl [1R,cis]-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate], fenfluthrin, and MTI-800 [1-(3-phenoxy-4-fluorophenyl)-4-(4-ethoxyphenyl)-4-methylpentane]. The onset of intoxication by pyrethroids in napts flies was markedly delayed, a finding that is consistent with the existence of a resistance mechanism involving reduced neuronal sensitivity. Resistance at the level of the nerve was confirmed by electrophysiological recordings of spontaneous and evoked activity in the dorsolongitudinal flight muscles of poisoned flies. Preparations from napts insects treated with fenfluthrin displayed longer latencies to the appearance of spontaneous activity and also an absence or reduction in burst discharges compared to equivalent preparations from susceptible individuals. These results are discussed in light of competing hypotheses concerning the mechanism underlying knockdown resistance and reduced nerve sensitivity in insects. 相似文献
88.
Glutathione (GSH) depletion sensitizes human lung carcinoma (A549-727) cells to the cytotoxic effects of Cd++. The effects of GSH depletion on Cd++ accumulation and Cd+-induced metallothionein (MT) content were investigated to determine the possible role of these Cd++ responses in the sensitization process. Cellular GSH was depleted to 20% to 25% of control levels with buthionine sulfoximine (BSO), or diethyl maleate (DEM), respectively. Neither treatment significantly affected Cd++-induced accumulation of exogenous35s-cysteine into intracellular MT in a dose-dependent fashion. The results indicate that neither enhanced Cd++ accumulation nor reduced MT synthesis plays a primary role in affecting enhanced Cd++ cytotoxicity in A549 cells with reduced GSH levels. Although BSO inhibition of GSH synthesis enhanced MT synthesis, it sensitized the cells to Cd++, which suggests an additive effect of GSH and MT in cadmium cytoprotection. This observation also raises the possibility that intracellular cysteine levels limit Cd++-induced MT accumulation rates.Abbreviations GSH
glutathione
- MT
metallothionein
- BSO
DL-buthionine-[S,R]-sulfoximine
- DMSO
dimethyl sulfoximine
- DEM
diethyl maleate
- NP-40
nonidet-P40
- PBS
phosphate buffered saline
- HBSS
Hank's balanced salt solution
- DTT
dithiothreitol
3. This work was presented in part at the 72nd Annual Meeting of the Federation of American Societies for Experimental Biology, Las Vegas, Nevada, May 1–5, 1988. 相似文献
89.
Joseph G. Major Jr. Melinda E. Wales John E. Houghton Julie A. Maley Jeffrey N. Davidson James R. Wild 《Journal of molecular evolution》1989,28(5):442-450
Summary Aspartate transcarbamoylase (ATCase, EC 2.1.3.2) is the first unique enzyme common to de novo pyrimidine biosynthesis and
is involved in a variety of structural patterns in different organisms. InEscherichia coli, ATCase is a functionally independent, oligomeric enzyme; in hamster, it is part of a trifunctional protein complex, designated
CAD, that includes the preceding and subsequent enzymes of the biosynthetic pathway (carbamoyl phosphate synthetase and dihydroorotase).
The complete complementary DNA (cDNA) nucleotide sequence of the ATCase-encoding portion of the hamster CAD gene is reported
here. A comparison of the deduced amino acid sequences of the hamster andE. coli catalytic peptides revealed an overall 44% amino acid similarity, substantial conservation of predicted secondary structure,
and complete conservation of all the amino acids implicated in the active site of theE. coli enzyme. These observations led to the construction of a functional hybrid ATCase formed by intragenic fusion based on the
known tertiary structure of the bacterial enzyme. In this fusion, the amino terminal half (the “polar domain”) of the fusion
protein was provided by a hamster ATCase cDNA subclone, and the carboxyl terminal portion (the “equatorial domain”) was derived
from a clonedpyrBI operon ofE. coli K-12. The recombinant plasmid bearing the hybrid ATCase was shown to satisfy growth requirements of transformedE. coli pyrB
− cells. The functionality of thisE. coli-hamster hybrid enzyme confirms conservation of essential structure-function relationships between evolutionarily distant
and structurally divergent ATCases. 相似文献
90.