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1.
2.
G D Hsiung 《The Yale journal of biology and medicine》1987,60(6):505-514
In 1911, the first retrovirus was described: the Rous sarcoma virus, an avian retrovirus. Forty years later the murine leukemic virus, a mouse retrovirus, was reported. Although many other retroviruses from non-primate species were identified during the 1960s, the first primate retrovirus was not recognized until it was isolated from a monkey tumor in 1970. The search for human retroviruses in human leukemic cells remained unsuccessful at that time. Facilitated by the discovery of T-cell growth factor, a substance used for the propagation of human leukocytes in cultures, the first human retrovirus was discovered in 1980. Soon thereafter, in 1983, another human retrovirus, human immunodeficiency virus (HIV), was reported and implicated as the etiologic agent of AIDS. The isolation and identification of HIV has stimulated much interest in the study of human retroviruses and the control of this new viral disease. 相似文献
3.
Mella Adlersberg Kuo-Peing Liu Shu-Chi Hsiung Yigal Ehrlich Hadassah Tamir 《Journal of neurochemistry》1987,49(4):1105-1115
The endogenous phosphorylation of serotonin binding protein (SBP), a soluble protein found in central and peripheral serotonergic neurons, inhibits the binding of 5-hydroxytryptamine (5-HT, serotonin). A protein kinase activity that copurifies with SBP (SBP-kinase) was partially characterized and compared with calcium/calmodulin-dependent protein kinase II (CAM-PK II). SBP itself is not the enzyme since heating destroyed the protein kinase activity without affecting the capacity of the protein to bind [3H]5-HT. SBP-kinase and CAM-PK II kinase shared the following characteristics: (1) size of the subunits; (2) autophosphorylation in a Ca2+-dependent manner; and (3) affinity for Ca2+. In addition, both forms of protein kinase phosphorylated microtubule-associated proteins well and did not phosphorylate myosin, phosphorylase b, and casein. Phorbol esters or diacylglycerol had no effect on either of the protein kinases. However, substantial differences between SBP-kinase and CAM-PK II were observed: (1) CAM enhanced CAM-PK II activity, but had no effect on SBP-kinase; (2) synapsin I was an excellent substrate for CAM-PK II, but not for SBP-kinase; (3) 5-HT inhibited both the autophosphorylation of SBP-kinase and the phosphorylation of SBP, but had no effect on CAM-PK II. These data indicate that SBP-kinase is different from CAM-PK II. Phosphopeptide maps of SBP and SBP-kinase generated by digestion with S. aureus V8 protease are consistent with the conclusion that these proteins are distinct molecular entities. It is suggested that phosphorylation of SBP may regulate the transport of 5-HT within neurons. 相似文献
4.
Hsiung HM 《Biotechnology advances》1986,4(1):1-11
Synthetic DNAs and oligonucleotides, which can be prepared conveniently by combining chemical synthesis and enzymatic methods, have been used extensively in recombinant DNA research. Examples include total gene synthesis, probes for the isolation of specific genes from cDNA or genomic libraries, linkers containing specific restriction sites for cloning, primers for DNA and RNA sequencing, and primers for the construction of specific mutations (either deletion, insertion or point mutations) by oligonucleotide-directed site-specific mutagenesis.This article reviews recent advances in the chemical and enzymatic synthesis of oligo- and polynucleotides and the application of synthetic DNA to the expression of foreign proteins. The synthesis of genes, including structural genes and regulatory genes are reviewed. Oligonucleotide-directed site-specific mutagenesis and use of synthetic DNA to optimize foreign protein expression are also discussed. 相似文献
5.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
6.
7.
Human cytomegalovirus maturational proteinase: expression in Escherichia coli, purification, and enzymatic characterization by using peptide substrate mimics of natural cleavage sites. 总被引:8,自引:8,他引:0
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P J Burck D H Berg T P Luk L M Sassmannshausen M Wakulchik D P Smith H M Hsiung G W Becker W Gibson E C Villarreal 《Journal of virology》1994,68(5):2937-2946
The proteolytic processing of the human cytomegalovirus (HCMV) assembly protein, resulting in truncation of its C terminus, is an essential step in virion maturation. The proteinase responsible for this cleavage is the amino-terminal half of the protein encoded by the UL80a open reading fame. We have obtained high expression levels of this 256-amino-acid HCMV proteinase, assemblin, in Escherichia coli. In addition to the 28-kDa proteinase, a 15-kDa protein comprising the first 143 amino acids and a 13-kDa protein comprising the last 113 amino acids of the 28-kDa HCMV proteinase were present. Both the 28-kDa proteinase and the 15-kDa protein were purified by a two-step chromatographic procedure utilizing anion exchange in urea and dithiothreitol and size exclusion in NaSCN and dithiothreitol. Activation of the purified 28-kDa proteinase required denaturation in urea as well as complete reduction of all five cysteine residues in the molecule. Removal of the urea by dialysis with retention of the reducing agent yielded an active proteinase. Addition of glycerol to 50% enhanced the activity. The HCMV proteinase cleaved the peptides RGVVNASSRLAK and SYVKASVSPE, which are mimics of the maturational (M)- and release (R)-site sequences, respectively, in the UL80a-encoded protein. The cleavage site in the peptides was at the same Ala-Ser scissile bond as observed in the UL80a protein. The Km value for the cleavage of RGVVNASSRLAK (M-site mimic) by the proteinase was similar to that for SYVKASVSPE (R-site mimic), but the turnover (kcat) of the M-site peptide mimic substrate by the proteinase was six to eight times faster. The peptide homologs of the herpes simplex virus type 1 M- and R-site sequences in the UL26-encoded protein were also cleaved by the HCMV proteinase, although at rates slower than those for the HCMV substrates. The HCMV proteinase was inhibited by Zn2+ and by alkylating agents, but only at very high inhibitor concentrations. The purified 15-kDa protein, subjected to the same activation conditions as the 28-kDa proteinase, had no enzymatic activity against the HCMV M- and R-site peptide substrates. 相似文献
8.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
9.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献
10.
The passive transport of water through the endothelial cell layer junctions is considered from the standpoint of hydrodynamic theories based on ultrastructural information. The local geometry of tight junctions based on molecular level forces and elastic membrane properties has been modeled and leads to estimates of the hydraulic resistance of the clefts. It is shown that the large resistance measured experimentally can be accounted for in this model. The transport of large macromolecules via vesicles which diffuse across the endothelial cell has been developed, but recent experimental data do not appear to support this mechanism as a primary pathway. Fused vesicles forming an open channel appear to be rare. Leaky junctions, such as around dying endothelial cells or produced by cytoskeletal changes within the cells, may be important in control of endothelial permeability. Another kind of model is a fiber matrix model of the endocapillary layer, extending into the intercellular clefts which can also account for the molecular seiving properties of the endothelial cell layer but may produce a large resistance to water flux. 相似文献