脱氧胞苷激酶基因的DNA探针的制备和纯化

本文报道乳酸杆菌脱氧胞苷激酶基因的DNA探针的人工合成和分离纯化以及杂交条件的探讨。结果表明:合成的探针可与酶解的核DNA杂交,显示出三条杂交带。     

SlNPV PK基因的部分序列分析

ＳｌＮＰＶ基因组ＤＮＡ的ＨｉｎｄⅢ－Ｘｂａ片段上含有部分的ＰＫ基因，ＳｌＮＰＶＰＫ的氨基酸序列与ＨａＮＰＶ，ＨｚＮＰＶＳｐｌｉＮＰＶ，ＡｆＮＰＶ，ＡｃＮＩＶ，ＬｄＮＰＶＰＫ氨基酸序列的同源性分别为４５％，４４％，８９％，３７％，３８％和３７％，其上含有蛋白激酶的特征序列ＩＶＨＡＮＤＶＫＬＥＮＶＬ。     

Pyruvate kinase inhibited by L-cysteine as a marker of tumorigenic human urothelial cell lines

Summary It was found that a decrease in electrophoretic mobility of pyruvate kinase (PK) isoenzyme, and an increase of the sensitivity of this enzyme to L-cysteine, were markers of immortalization and tumorigenic properties, respectively, in human urothelial cell lines characterized by different grades of transformation (TGr) in vitro.     

The Janus kinase family of protein tyrosine kinases and their role in signaling

In the early 1990s, the search for protein kinases led to the discovery of a novel family of non-receptor tyrosine kinases, the Janus kinases or JAKs. These proteins were unusual because they contained two kinase homology domains and no other known signaling modules. It soon became clear that these were not ‘just another’ type of kinase. Their ability to complement mutant cells insensitive to interferons and to be activated by a variety of cytokines demonstrated their central signaling function. Now, as we approach the end of the decade, it is evident from biochemical studies to knockout mice that JAKs play non-redundant functions in development, differentiation, and host defense mechanisms. Here, recent progress is reviewed, with particular emphasis on structure-function studies aimed at revealing how this family of tyrosine kinases is regulated.     

The molecular basis and clinical aspects of Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is a classic, but not widely known hereditary trait. Its clinical hallmarks are intestinal hamartomatous polyposis and melanin pigmentation of the skin and mucous membranes. In addition, PJS predisposes to cancer . The most common malignancies are small intestinal, colorectal, stomach and pancreatic adenocarcinomas. Other cancer types that probably occur in excess in PJS families include breast and uterine cervical cancer, as well as testicular and ovarian sex cord tumors. The relative risk of cancer may be as high as 18 times that of the general population, and the cancer patients' prognosis is reduced. Recently, the predisposing locus was mapped to 19p13.3 using a novel method. Subsequently, the causative gene was shown to be LKB1 (a.k.a. STK11), a serine/threonine kinase of unknown function. Although preliminary reports seem to suggest a minor role for LKB1 in sporadic tumorigenesis, further investigations are needed. Received 12 October 1998; received after revision 30 November 1998; accepted 30 November 1998     

ＣaＭ激酶及其在植物体内的功能

介绍了CaM激酶的结构和生化特点，以及植物体内CaM激酶的研究进展。从植物细胞信号转导、发育和基因表达等３个方面讨论了CaM激酶激酶在植物体内的生理功能。     

Thymidine kinase gene mutation leads to reduced virulence of pseudorabies virus

To explore correlation between the tk gene structure of pseudorabies virus (PRV) and its virulence, to study the effect of the gene mutation on PRV biological properties, and to investigate mechinism of reduced virulence, thymidine kinase (TK)-deficient mutant of pseudorabies virus strain Hubei (PRV HB) was isolated by selection for resistance to 5-bromodeoxyuridine. The tk genes of PRV HB and its TK^― mutant were cloned and sequenced. 1587 base pairs of the tk gene and flanking regions of wild-type (wt) virus were sequenced, which included an open reading frame (ORF) of 1098 bp encoding a protein of 366 amino acids. The ORF contained two 137-bp repeated sequences, which were connected by an adenosine. 1458 bp of the tk and flanking regions of TK^― mutant were sequenced. Analysis of the tk gene sequence of TK^― mutant indicated that one of 137 bp repeated sequence and the connecting adenosine in the tk gene of the wt virus was deleted and a repeated sequence of 8 nucleotides (GCGCGCC) was inserted. All other nucleotides of TK^―mutant were identical to that of wt virus. Deletion and insertion of the nucleotide sequence resulted in a frameshift and a premature chain termination, and the resultant TK protein was not active. Analysis of the amino acid sequence revealed that TK protein of PRV HB contained the conserved consensus sequence of herpesviral TKs and an additional conserved-DHR-motif. The results of this work also indicated that TK^― mutant was genetically stable. Compared to PRV HB, virulence of TK^― mutant was greatly decreased. Mice vaccinated with TK^― mutant were completely protected against a lethal challenge with virulent PRV (HB).     

Mechanical and biochemical characterization of the contraction elicited by a calcium-independent myosin light chain kinase in chemically skinned smooth muscle

Summary The contraction induced by a Ca²⁺-independent myosin light chain kinase (MLCK-) was characterized in terms of isometric force (F_o), immediate elastic recoil (SE), unloaded shortening velocity (V_us), shortening under a constant load and ATPase activity of chemically skinned smooth muscle preparations. These parameters were compared to those measured in a Ca²⁺-induced contraction to assess the nature of cross bridge interaction in the MLCK-induced contraction. F_o developed in chicken gizzard fibers as well as SE were similar in contractions elicited by either agent. V_us in the contraction induced by MLCK-(0.36 mg/ml) was similar though averaged 39.3±8.9% less than V_us induced by Ca²⁺ (1.6x10^–6M) in the control fibers. Addition of Ca²⁺ (1.6x10^–6M) to a contraction induced by MLCK-resulted in small increases in both F_o and V_us. Shortening under a constant load was similar for both types of contractions. The contraction induced by MLCK-was accompanied by an increased rate of ATP hydrolysis. The MLCK-induced contraction is thus kinetically similar though not identical to a contraction induced by Ca²⁺. We conclude that with respect to actin-myosin interaction, MLCK- and Ca²⁺-induced contractions are similar.     

Oscillatory change of SR-protein kinase activities during oocyte maturation meiosis in fish

The SR-protein kinase activity was analyzed and the cytological changes were observed during oocyte maturation in bisexual transparent color crucian carp ( Carassius auratus color variety) . The results revealed that the SR-protein kinase activity was sensitive to the artificially induced spawning hormones, and the change of oscillatory activity was similar to that of the maturation-promoting factor (MPF) kinase that regulates meiotic cell cycle in fish.     

选择性BCR-ABL酪氨酸激酶抑制剂体外筛选体系的建立

BCR—ABL融合基因表达的肿瘤蛋白是慢性髓性白血病的主要致病因素，应用人BCR—ABL，基因转染的细胞株FD—rv 210与其祖代细胞FDC—P1细胞组成的配对细胞株和不同的培养条件，建立了一个BCR—ABL酪氨酸激酶抑制剂的体外筛选体系，用于检测BCR—ABL酪氨酸激酶抑制剂的选择性，发现两种BCR—ABL，酪氨酸激酶抑制剂AG957和AG490，对BCR—ABL阳性细胞和阴性细胞的增殖抑制作用相似；培养体系中有无祖代细胞增殖所需的细胞因子，对其增殖抑制作用无影响；AG957短时作用于细胞即发生不可逆的增殖抑制现象，与已知的选择性BCR—ABL酪氨酸激酶抑制剂STI571特性明显不同，提示这两种抑制剂作用呈非选择性，所建立的体外培养体系及不同的培养条件的组合，可用于筛选各种选择性的BCR—ABL酪氨酸激酶抑制剂。