The neu oncogene encodes an epidermal growth factor receptor-related protein

The neu oncogene is repeatedly activated in neuro- and glioblastomas derived by transplacental mutagenesis of the BDIX strain of rat with ethylnitrosourea. Foci induced by the DNAs from such tumours on NIH 3T3 cells contain the neu oncogene and an associated phosphoprotein of relative molecular mass 185,000 (p185). Previous work has shown that the neu gene is related to, but distinct from, the gene encoding the EGF receptor (c-erb-B). Here we describe a neu complementary DNA clone isolated from a cell line transformed by this oncogene; the clone has biological activity in a focus-forming assay. The nucleotide sequence of this clone predicts a 1,260-amino-acid transmembrane protein product similar in overall structure to the EGF receptor. We found that 50% of the predicted amino acids of neu and the EGF receptor are identical; greater than 80% of the amino acids in the tyrosine kinase domain are identical. Our results suggest strongly that the neu gene encodes the receptor for an as yet unidentified growth factor.     

Escherichia coli cell-division gene ftsZ encodes a novel GTP-binding protein.

Escherichia coli divides by forming a septum across the middle of the cell. The biochemical mechanism underlying this process is unknown. Genetic evidence suggests that of all the fts (filamentation temperature sensitive) genes involved in E. coli cell division, ftsZ plays a central role at the earliest known step of septation. Here we show that FtsZ protein binds GTP in vitro using unusual sequence elements. In contrast, such binding to the product of the conditional-lethal ftsZ84 allele is impaired. Purified FtsZ displays a Mg(2+)-dependent GTPase activity which is markedly reduced in the FtsZ84 protein. FtsZ copurifies with near stoichiometric amounts of noncovalently-bound GDP, implying the presence of a GTPase cycle in vivo, similar to that known for signal-transducing GTP-binding proteins. We also show that a small fraction of FtsZ exists as a distinct membrane-associated species that binds GTP. The membrane association of FtsZ and the known ability of GTPases to act as molecular switches implicate FtsZ in a GTP-activated signal transduction pathway that may regulate the start of septation in E. coli.     

An LFA-3 cDNA encodes a phospholipid-linked membrane protein homologous to its receptor CD2

Recently the human T cell erythrocyte receptor CD2 has been shown to bind human erythrocytes through LFA-3, a heavily glycosylated surface protein of broad tissue distribution. CD2-LFA-3 interactions are important for cytolytic conjugate formation, for thymocyte adhesion, and for T cell activation. A complementary DNA clone encoding LFA-3 was isolated using a complementary DNA clone encoding LFA-3 was isolated using a novel transient expression system of mouse cells. The cDNA encodes a phospholipid-linked membrane protein whose extracellular domain shares significant homology with CD2. As CD2 is homologous with the neural cell adhesion molecule NCAM in immunoglobulin-like domains, cellular adhesion molecules in both neural and lymphoid tissues could have a common ancestor.     

C. elegans cell-signalling gene sem-5 encodes a protein with SH2 and SH3 domains.

The induction of the hermaphrodite vulva and the migration of the sex myoblasts in the nematode Caenorhabditis elegans are both controlled by intercellular signalling. The gonadal anchor cell induces formation of the vulva from nearby hypodermal cells, and a set of somatic gonadal cells attract the migrating sex myoblasts to their final positions. Many genes required for vulval induction have been identified, including the let-23 receptor tyrosine kinase gene and the let-60 ras gene. We report here the identification and characterization of a new gene, sem-5 (sem, sex muscle abnormal), that acts both in vulval induction and in sex myoblast migration. On the basis of its DNA sequence, sem-5 encodes a novel 228-amino-acid protein which consists almost entirely of one SH2 (SH, src homology region) and two SH3 domains. SH2 and SH3 domains are present in many signalling proteins regulated by receptor and non-receptor tyrosine kinases. Mutations that impair sem-5 activity alter residues that are highly conserved among different SH2 and SH3 domains. Our results indicate that the sem-5 gene encodes a novel protein that functions in at least two distinct cell-signalling processes.     

A yeast gene encoding a protein homologous to the human c-has/bas proto-oncogene product

Organisms amenable to easy genetic analysis should prove helpful in assessing the function of at least those proto-oncogene products which are highly conserved in different eukaryotic cells. One obvious possibility is to pursue the matter in Drosophila melanogaster DNA, which has sequences homologous to several vertebrate oncogenes. Another is to turn to the yeast Saccharomyces cerevisiae, if it contains proto-oncogene sequences. Here we report the identification of a gene in S. cerevisiae which codes for a 206 amino acid protein (YP2) that exhibits striking homology to the p21 products of the human c-has/bas proto-oncogenes and the transforming p21 proteins of the Harvey (v-rasH) and Kirsten (v-rasK) murine sarcoma viral oncogenes. The YP2 gene is located between the actin and the tubulin gene on chromosome VI and is expressed in growing cells. The protein it encodes might share the nucleotide-binding capacity of p21 proteins.     

旋转填充床中O3/Fenton工艺处理酸性黄23印染废水的研究

以超重力旋转填充床（RPB）为反应装置,结合Fenton试剂,研究了臭氧高级氧化技术处理酸性黄23印染废水的效果。考察了初始pH值、Fe ²⁺离子浓度、H₂O₂浓度、臭氧质量浓度、旋转填充床转速、NaCl质量浓度、KH₂PO₄质量浓度、Na₂SO₄质量浓度等因素对脱色率和COD去除率的影响。实验结果表明,当转速为1000r/min、pH=4、Fe ²⁺浓度为0.6mmol/L、H2O2浓度为1.5mmol/L、O3质量浓度为40mg/L、液体流量为30L/h时,酸性黄23的脱色率可达到90%以上,溶液COD去除率可达到33%;随着NaCl、KH₂PO₄质量浓度的增加,酸性黄23脱色率与溶液COD去除率不断减小;改变Na₂SO₄质量浓度,酸性黄23脱色率与溶液COD去除率变化不大。     

一种有效的富氢中选择氧化CO催化剂Au-CuO/Al2O3

采用等体积浸渍法制备了1.0%Au-CuO/Al2O3催化剂,考察了不同Au与Cu的原子比对催化剂在富氢气氛下选择氧化CO性能的影响,并对该催化剂稳定性进行了初步测试.结果表明,该催化剂在30 ℃～85 ℃范围内可以将CO浓度由1.0%降至0.005%以下.催化剂在80 ℃,模拟气氛条件下10 h内失活很小.通过BET、XRD、UV-vis漫反射等表征发现:催化剂体系中Cu以CuO的形式存在,较小粒子的Au在该反应中表现出较好的活性与选择性.