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1.
Circumsporozoite protein of Plasmodium berghei: gene cloning and identification of the immunodominant epitopes. 总被引:12,自引:2,他引:10 下载免费PDF全文
D J Eichinger D E Arnot J P Tam V Nussenzweig V Enea 《Molecular and cellular biology》1986,6(11):3965-3972
The gene encoding the circumsporozoite (CS) protein of the rodent malaria parasite Plasmodium berghei was cloned and characterized. A cDNA library made from P. berghei sporozoite RNA was screened with a monoclonal antibody for expression of CS protein epitopes. The resulting cDNA clone was used to isolate the CS protein gene from a lambda library containing parasite blood-stage DNA. The CS protein gene contains a central region encoding two types of tandemly repeated amino acid units, flanked by nonrepeated regions encoding amino- and carboxy-terminal signal and anchorlike sequences, respectively. One of the central repeated amino acid unit types contains the immunodominant epitopes. 相似文献
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Pro-opiomelanocortin (POMC) was expressed in CV-1 (green monkey kidney) cells using a vaccinia virus transient expression system [(1986) Proc. Natl. Acad. Sci. USA 83, 8122]. The system involved infection of cells with a recombinant vaccinia virus carrying the T7 RNA polymerase gene and transfection with a plasmid containing the mouse POMC sequence flanked by the T7 RNA polymerase promoter at its 5'-end and the T7 RNA polymerase terminator at its 3'-end. Assay of the medium from transfected cells showed that 1-2 micrograms of immunoreactive ACTH was produced/10(6) cells. Analysis of the same medium by SDS-PAGE/Western blots revealed a band of 30-36 kDa, which was immunostained with both ACTH and beta-endorphin antisera. Labeling the transfected cells with [3H]Arg, followed by immunoprecipitation and SDS-PAGE showed the synthesis of a major peak of POMC, 33 kDa. Purified [3H]POMC expressed by CV-1 cells was cleaved in vitro by bovine intermediate lobe secretory vesicle pro-opiomelanocortin-converting enzyme to ACTH intermediates (19-25 kDa), beta-lipotropin and beta-endorphin. Thus, this work has demonstrated a technique for expressing microgram quantities of prohormones in mammalian cells, suitable for use as substrates for prohormone-converting enzymes in vitro. 相似文献
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G S Tam G S Marks J F Brien K Nakatsu 《Canadian journal of physiology and pharmacology》1987,65(7):1478-1483
The biotransformation of isosorbide dinitrate (ISDN) by various tissues of the rabbit and rat was examined. Incubation of 2 X 10(-7) M ISDN at 37 degrees C with tissue homogenates of liver, lung, kidney, intestine, skeletal muscle, aorta, and erythrocytes from the rabbit and rat resulted in a significant disappearance of ISDN after a 30-min incubation (also, 5-min incubation for liver). The disappearance of ISDN in each tissue homogenate was accompanied by an equimolar production of the mononitrate metabolites, isosorbide-2-mononitrate (2-ISMN) and isosorbide-5-mononitrate (5-ISMN), with the exception of liver homogenates where the loss of ISDN could not be accounted for by mononitrate formation. The relative rate of ISDN disappearance in various tissue homogenates was for the male rabbit, liver greater than lung approximately intestine greater than kidney greater than erythrocytes approximately skeletal muscle approximately aorta; for the female rabbit, liver greater than kidney approximately lung approximately intestine greater than erythrocytes approximately skeletal muscle approximately aorta; and for the male rat, liver greater than intestine greater than erythrocytes greater than skeletal muscle greater than lung approximately kidney. A sex difference in the percent disappearance of ISDN was observed in homogenates of lung and intestine from male and female rabbits. In addition, a sex difference in the ratio of metabolite (2-ISMN/5-ISMN) formed by denitration of ISDN was seen in homogenates of lung, skeletal muscle, and erythrocyte lysate.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Summary A voltage-dependent anion-selective channel, VDAC, is found in outer mitochondrial membranes. VDAC's conductance is known to decrease as the transmembrane voltage is increased in either the positive or negative direction. Charged groups on the channel may be responsible for this voltage dependence by allowing the channel to respond to an applied electric field. If so, then neutralization of these charges would eliminate the voltage dependence. Channels in planar lipid bilayers which behaved normally at pH 6 lost much of their voltage dependence at high pH. Raising the pH reduced the steepness of the voltage dependence and raised the voltage needed to close half the channels. In contrast, the energy difference between the open and closed state in the absence of a field was changed very little by the elevated pH. The groups being titrated had an apparent pK of 10.6. From the pK and chemical modification, lysine epsilon amino groups are the most likely candidates responsible for VDAC's ability to respond to an applied electric field. 相似文献
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Infertility induced in rats by immunization with synthetic peptide segments of a sperm protein. 总被引:3,自引:0,他引:3
G Vanage Y A Lu J P Tam S S Koide 《Biochemical and biophysical research communications》1992,183(2):538-543
Three peptide segments (YAL-198, YAL-201 and YAL-212) corresponding to the extracellular domain of a human sperm protein designated as YWK-II antigen were synthesized as multiple antigen peptide (MAP). Male and female rats were immunized with the YWK-II-MAPs and fertility determined. In a group of 12 female rats immunized with YAL-198, seven animals were infertile and two animals were subfertile. When immunized with YAL-201 and YAL-212, 4 and 2 animals were infertile, respectively. In a group of 15 males immunized with YAL-198, 2 animals were infertile and 6 were subfertile. Two animals immunized with YAL-201 were subfertile. All control male and female rats immunized with bovine serum albumin and adjuvant were fertile. Sera obtained from infertile rats immunized with YAL-198 contained higher titers of antibodies compared to those obtained from fertile animals. The present study shows that immunization with synthetic peptide segments of a sperm protein can effectively reduce fertility. 相似文献
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