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111.
Isolation and characterization of human VkIII germ-line genes. Implications for the molecular basis of human VkIII light chain diversity 总被引:18,自引:0,他引:18
P P Chen K Albrandt T J Kipps V Radoux F T Liu D A Carson 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(5):1727-1733
To understand the relative importance of germ-line genes in the generation of the functional human antibody repertoire, it is first necessary to define the number of variable region genes and to determine their fine structure. We have focused on the human VkIII variable region gene family because of its association with autoantibodies. A human genomic library was screened with a VkIII cDNA probe and subsequently with a VkIII germ-line gene probe. Seven different VkIII clones were isolated and characterized by restriction mapping and sequence analyses. Three clones have identical restriction enzyme sites over a 12-kilobase (kb) region, contain identical sequences over an 895-base pair (bp) region, and thus are likely to be different isolates of the same human VkIII gene. Another two clones have identical restriction enzyme sites over a 5-kb region, are identical over a stretch of 905 bp sequenced, and likely represent independent isolates of another human VkIII gene. The remaining two VkIII clones consist of two additional VkIII genes which are homologous to each other, but are quite different from the first two VkIII genes. Thus, four new human VkIII genes were defined. Together with four other VkIII genes previously isolated by other investigators, a total of eight human VkIII germ-like genes have now been described. A comparison of the deduced amino acid sequences of these genes with the reported amino acid sequences of all human VkIII light chains suggests that at least one additional VkIII gene exists in the germ line. Among the eight identified human germ-line VkIII genes, three are pseudogenes. Of the remaining five potential functional genes, one gene seems to encode a majority of the VkIII light chains which have been sequenced. Possible explanations for this phenomenon are discussed. 相似文献
112.
Y Suzuki C M Liu L P Chen D Ben-Nathan E F Wheelock 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(9):3146-3152
L5178Y lymphoma cells are restrained from progressive growth in peritoneal cell ("in vitro tumor-regressor" PC) cultures prepared from many DBA/2 mice which harbor the tumor cells in the peritoneal cavity in a tumor-dormant state. Treatment of these PC cultures with 'antibodies to murine interferon-gamma (MuIFN-gamma) and murine tumor necrosis factor (MuTNF) but not with antibody to interleukin 2 (IL-2) receptors eliminated the restraint on tumor cell growth and permitted their progressive proliferation. L5178Y cells were found to be resistant to the direct toxic effects of large concentrations (3,000 U/ml) of MuIFN-gamma and of MuTNF, either alone or in combination. Treatment of PC cultures from tumor-dormant mice, in which tumor cells grew progressively ("in vitro tumor-progressor"), but not PC cultures from normal mice, with exogenous MuIFN-gamma resulted in a marked inhibition of tumor cell growth. The MuIFN-gamma-induced cytotoxic activity was cell-mediated since no soluble tumor-cytotoxic factors could be detected in the cultures. MuIFN-gamma induced cytotoxic activity in plastic-adherent peritoneal cell (AD-PC) cultures, but induced no cytotoxic activity in nonadherent-PC cultures unless small numbers (2%) of AD-PC were present, and inclusion of antibody to MuTNF in these mixed PC cultures blocked the development of cytotoxic activity. Antibody to MuTNF also blocked the development of cytotoxic activity in cultures of MuIFN-gamma-treated whole PC and AD-PC from tumor-dormant mice. These results indicate that MuIFN-gamma and MuTNF are both important in restraining tumor cell growth in PC cultures from tumor-dormant mice, and that MuIFN-gamma requires the presence of MuTNF to induce cytotoxic activity in these cultures. 相似文献
113.
We constructed a recombinant gene encoding an immunoglobulin (Ig) heavy chain consisting of the variable region from the phosphorylcholine (PC)-specific secreting myeloma MOPC167 and the epsilon constant region from SJL mice. This gene, cloned into the shuttle vector pSV2gpt, was transfected into J558L myeloma cells, and stable transformants that expressed the epsilon gene were cloned. The IgE heavy chain in these transformants is associated with the endogenous lambda light chain and is secreted as an intact IgE molecule. However, the secreted IgE does not bind to PC conjugated to bovine serum albumin (PC-BSA). The MOPC167 kappa chain gene was cloned into the shuttle vector pSV2neo and was transfected into the epsilon heavy-chain transformant. Stable transformants were cloned that expressed both the epsilon heavy chain and the kappa light chain. IgE secreted from such a transformant was shown to bind to PC-BSA. Both types of secreted recombinant IgE bound to rat basophilic leukemia (RBL) cells, but only the IgE produced by the cell line transformed with the MOPC167 kappa gene could be cross-linked with PC-BSA to cause serotonin release. 相似文献
114.
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
115.
Drug plasma protein binding and pharmacokinetics 总被引:1,自引:0,他引:1
116.
中国木兰属和含笑属导管分子的比较解剖 总被引:4,自引:0,他引:4
本文对我国木兰科的39种木兰属和含笑属植物次生木质部的导管分子进行了初步分析。两属导管分子的长度和宽度略有差异。木兰属中多数种的导管分于有单穿孔板,但有的可见到梯状穿孔板。含笑属植物的导管分子大多具有梯状穿孔板,仅有一种可看到单穿孔板。在具有梯状穿孔板的木兰属植物中,穿孔板的横隔数目较含笑属的多。木兰属的导管壁上一般无螺纹加厚;含笑属则相反。此外,在两属之间,导管尚存在一些其它差异。 相似文献
117.
石刁柏已形成细胞的幼嫩胚乳,接种在附加有不同浓度的生长素(NAA)和细胞分裂素(BA)的 MS 培养基上,获得了愈伤组织。愈伤组织的诱导频率随生长素的浓度不同而异,可达65.9—83.1%。将胚乳愈伤组织转移到降低了生长素浓度或只含有低浓度生长素的分化培养基上,可陆续分化芽、根、芽丛和少量胚状体,个别的芽和胚状体能发育成小植株。切取1.5—5cm 长的芽,接种在诱导根的培养基上,或在 IBA50ppm 溶液中浸泡2小时,转移到 MS 基本培养基上,部分芽能生根形成完整植株。 相似文献
118.
The kinetic characteristics and the effect of endotoxin administration on the enzymatic methylation of phospholipids in dog heart microsomes were studied using S-adenosyl-L-[methyl-3H]methionine as a methyl donor. Kinetic studies in control dogs reveal that the stepwise methylation of phosphatidylethanolamine to phosphatidylcholine was catalyzed by three different enzymes. Methyltransferase I catalyzed the methylation of phosphatidylethanolamine to phosphatidyl-N-monomethylethanolamine, had a very low Km (approximately 1.5 microM) for S-adenosylmethionine, and a pH optimum of 6.5, and it was stimulated by Mg2+ and Ca2+. Methyltransferase II catalyzed the methylation of phosphatidyl-N-monomethylethanolamine to phosphatidyl-N,N-dimethylethanolamine, had a low Km (8-12 microM) for S-adenosylmethionine, and a pH optimum of 8.5, and it was stimulated by low concentrations (less than 1 mM) of Ca2+ but was unaffected by Mg2+. Methyltransferase III catalyzed the formation of phosphatidylcholine from phosphatidyl-N,N-dimethylethanolamine, had a high Km (approximately 33 microM) for S-adenosylmethionine, and a pH optimum of 9.5, and it was unaffected by Mg2+ or Ca2+. Experiments with trypsin digestion indicate that methyltransferases I and III were partially embedded while methyltransferase II was completely exposed to the surface of the membrane. Endotoxin administration (2 and 4 hr) decreased the Km and Vmax by 30 to 36% and 24 to 37.7%, respectively, for S-adenosylmethionine. Since the enzymatic methylation of phospholipids has been implicated to play an important role in the regulation of membrane structure and function, the endotoxin-induced decreases in the Km and Vmax of phospholipid-methylating enzymes in dog heart microsomes may contribute to the development of myocardial dysfunction in endotoxin shock. 相似文献
119.
Expression of transforming growth factor alpha (TGF alpha) in differentiated rat mammary tumors: estrogen induction of TGF alpha production 总被引:4,自引:0,他引:4
S C Liu B Sanfilippo I Perroteau R Derynck D S Salomon W R Kidwell 《Molecular endocrinology (Baltimore, Md.)》1987,1(10):683-692
Primary well-differentiated dimethylbenzene alpha-anthracene (DMBA)-or nitrosomethylurea (NMU)-induced rat mammary adenocarcinomas that are estrogen dependent possess biologically active and immunoreactive transforming growth factor alpha (TGF alpha), which can be detected in a sort agar growth-promoting assay and by a specific liquid-phase competitive RIA, respectively. In contrast, tissue extracts prepared from transplantable undifferentiated DMBA-I and NMU-II rat mammary carcinomas that are estrogen independent and metastatic exhibit low or undetectable levels of TGF alpha. In addition, the primary DMBA- and NMU-induced rat mammary adenocarcinomas express a specific 4.8-kilobase TGF alpha mRNA species, whereas little or no TGF alpha mRNA can be detected in the transplantable DMBA-I and NMU-II tumors. Primary tumors synthesize type IV basement membrane collagen, whereas the transplantable tumors elaborate very little type IV collagen. Either TGF alpha or estrogens can differentially enhance the synthesis of type IV collagen by 0.5- to 4-fold over total protein synthesis in primary cultures of normal mouse mammary epithelial cells or in primary NMU-induced tumor cells, respectively. Therefore, TGF alpha could function as an estrogen-inducible autocrine growth factor for well differentiated rat mammary tumor cells by its ability to selectively regulate type IV collagen synthesis. Estrogens can modulate TGF alpha production in vivo in primary DMBA-induced rat mammary tumors, because ovariectomy results in a rapid decline (within 6 h) of TGF alpha mRNA levels. This response to estrogens can also be observed in vitro. Primary DMBA- or NMU-induced rat mammary tumor cells cultured in the presence of 17 beta-estradiol (10(-8) M) for 4 days show an increase in the level of TGF alpha mRNA over cells not treated with estrogen. This increase in TGF alpha mRNA is paralleled by a 2- to 3-fold increase in the levels of immunoreactive TGF alpha that can be detected and in the conditioned medium from estrogen-treated cells. These results suggest that TGF alpha may be an adjunct marker for those mammary tumors that are well differentiated adenocarcinomas and estrogen dependent and that estrogen-independent tumors do not constitutively produce TGF alpha or express TGF alpha mRNA. 相似文献
120.
Urea caused dissociation of alpha 2-macroglobulin (alpha 2M) into half-molecules (two disulfide-bonded subunits) as revealed by gel electrophoresis. The fraction of whole molecules remaining decreased with increasing urea concentration. Half-dissociation occurred at about 2.2 M. The ability of alpha 2M to inhibit trypsin also decreased with increasing urea concentration, but the activity-urea curve was shifted to the right as compared to the dissociation-urea curve. Thus, at 3 M urea, gel electrophoresis showed only 6.6% whole molecules, whereas the trypsin inhibitory activity was 95% of that in buffer with no urea, suggesting that half-molecules retain activity. In addition, complexes formed in urea with 125I-labeled trypsin were observed to migrate as half-molecules even though only 50% of such complexes were covalent. These results are surprising in light of the report by Gonias and Pizzo [Gonias, S., & Pizzo, S. (1983) Biochemistry 22, 536-546] that half-molecules formed by mild reduction are active; reduction is assumed to divide the molecule along an axis orthogonal to the break caused by urea. This suggests that active half-molecules can be formed by splitting either the covalent or noncovalent bonds that hold the subunits together. A model is proposed that can account for this possibility. It has the same dimensions and symmetry as a previous model of Feldman et al. [Feldman, S.R., Gonias, S.L., & Pizzo, S.V. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5700-5704] and accounts in a similar way for previous functional studies of the protein.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献