Drosophila contains three genes that encode distinct isoforms of protein phosphatase 1

The sequences of two Drosophila and one rabbit protein phosphatase (PP) 1 catalytic subunits were determined from their cDNA. The sequence of Drosophila PP1 alpha 1 was deduced from a 2.2-kb cDNA purified from an embryonic cDNA library, while that for Drosophila PP1 beta was obtained from overlapping clones isolated from both a head cDNA library and an eye imaginal disc cDNA library. The gene for Drosophila PP1 alpha 1 is at 96A2-5 on chromosome 3 and encodes a protein of 327 amino acids with a calculated molecular mass of 37.3 kDa. The gene for Drosophila PP1 beta is localized at 9C1-2 on the X chromosome and encodes a protein of 330 amino acids with a predicted molecular mass of 37.8 kDa. PP1 alpha 1 shows 96% amino acid sequence identity to PP1 alpha 2 (302 amino acids), an isoform whose gene is located in the 87B6-12 region of chromosome 3 [Dombrádi, V., Axton, J. M., Glover, D.M. Cohen, P.T.W. (1989) Eur. J. Biochem. 183, 603-610]. PP1 beta shows 85% identity to PP1 alpha 1 and PP1 alpha 2 over the 302 homologous amino acids. These results demonstrate that at least three genes are present in Drosophila that encode different isoforms of PP1. Drosophila PP1 alpha 1 and PP1 beta show 89% amino acid sequence identity to rabbit PP1 alpha (330 amino acids) [Cohen, P.T.W. (1988) FEBS Lett. 232, 17-23] and PP1 beta (327 amino acids), respectively, demonstrating that the structures of both isoforms are among the most conserved proteins known throughout the evolution of the animal kingdom. The presence of characteristic structural differences between PP1 alpha and PP1 beta, which have been preserved from insects to mammals, implies that the alpha and beta isoforms may have distinct biological functions.     

Molecular characterization of a putative peroxidase gene of Drosophila melanogaster.

We have identified genomic clones and corresponding cDNAs that encode a putative peroxidase of Drosophila melanogaster. The gene (DmPO) appears as a single copy gene located on the third chromosome at position 89 D/E. It is interrupted by seven small introns and one unusually large 5' intron (about 11 kb). Sequence analysis of the cDNA showed an open reading frame of 690 amino acids resulting in a protein of 77 kDa. The deduced amino acid sequence reveals an overall homology to myeloeosinophil and thyroid peroxidase, a human superfamily of peroxidases.     

人类Connexin基因家族新成员-Cx44基因的克隆和特性分析

用绵羊和牛的Cx44基因(connexin 44 protein gene)序列对NCBI数据库进行Blast检索,得到一个相似性很高的人DNA序列(Human Genome Bank:AL138688),用GENSCAN程序分析AL138688,推测AL138688中包含一个编码区由1个外显子构成的基因——Cx44基因。人Cx44基因的开放阅读框为1320bp,推测编码435个氨基酸。用PROMOTORSCAN程序分析了其启动子。人Cx44基因与绵羊Cx44基因在1320bp有84.75％的一致性,其表达的蛋白有83％的一致性。用Map View将人的Cx44基因定位于13号染色体。     

The fat tumor suppressor gene in Drosophila encodes a novel member of the cadherin gene superfamily

Recessive lethal mutations in the fat locus of Drosophila cause hyperplastic, tumor-like overgrowth of larval imaginal discs, defects in differentiation and morphogenesis, and death during the pupal stage. Clones of mutant cells induced by mitotic recombination demonstrate that the overgrowth phenotype is cell autonomous. Here we show that the fat locus encodes a novel member of the cadherin gene superfamily: an enormous transmembrane protein of over 5000 amino acids with a putative signal sequence, 34 tandem cadherin domains, four EGF-like repeats, a transmembrane domain, and a novel cytoplasmic domain. Two recessive lethal alleles contain alterations in the fat coding sequence, and the dominant fat allele, Gull, contains an insertion of a transposable element in the 33rd cadherin domain. Thus, this novel member of the cadherin gene superfamily functions as a tumor suppressor gene and is required for correct morphogenesis.     

Sequence of a Drosophila Ligand-Gated Ion-Channel Polypeptide with an Unusual Amino-Terminal Extracellular Domain

Abstract: We report the isolation of a full-length clone from a Drosophila melanogaster head cDNA library that encodes a 614-residue polypeptide that exhibits all of the features of a ligand-gated chloride-channel/receptor subunit. This polypeptide, which has been named GRD (denoting that the polypeptide is a GABA_A and glycine receptor-like subunit of Drosophila) , displays between 33 and 44% identity to vertebrate GABA_A and glycine receptor subunits and 32–37% identity to the GABA_A receptor-like polypeptides from Drosophila and Lymnaea. It is interesting that the large amino-terminal, presumed extracellular domain of the GRD protein contains an insertion, between the dicysteine loop and the first putative membrane-spanning domain, of 75 amino acids that is not found in any other ligand-gated chloride-channel subunit. Analysis of cDNA and genomic DMA reveals that these residues are encoded by an extension of an exon that is equivalent to exon 6 of vertebrate GABA_A and glycine receptor genes. The gene (named Grd) that encodes the Drosophila polypeptide has been mapped, by in situ hybridization, to position 75A on the left arm of chromosome 3.     

富亮氨酸重复超家族新成员LRRC4的克隆与在脑瘤中的表达分析

在染色体7q31-32多种肿瘤杂合性丢失（loss of heterozygosity,LOH）高频区,采用表达序列标签（expressed sequence tag,EST）介导的定位候选克隆策略获得了一个定位于人染色体7q31-32的新基因（GenBank 登录号: AF196976）.该基因编码653个氨基酸,蛋白质理论pI/m:6.58/72.7 ku.它包含七个典型的LRR、一个IgC2样结构域.此外,它还包含一个N端信号肽、一个C端跨膜区.其结构特征表明它是富亮氨酸重复（leucine-rich repeat,LRR）超家族的新成员.经过人类基因组命名委员会的同意,将该基因命名为LRRC4.此外,通过序列相似性匹配还获得了定位于小鼠6号染色体的LRRC4的同源基因（GenBank 登录号: AF290542）.RNA印迹和RT-PCR检测发现LRRC4在正常人脑组织相对特异表达,而在多种原发性脑瘤表达明显下调或缺失.综合考虑LRRC4基因的序列特征及表达谱,提示LRRC4基因可能在神经系统中发挥重要作用.     

Nucleotide sequence encoding the precursor of the small subunit of ribulose 1,5-bisphosphate carboxylase from Lemna gibba L.G-3

We have sequenced a cDNA clone, pLgSSU, which encodes the small subunit of ribulose 1,5-bisphosphate carboxylase of Lemna gibba L.G-3 a monocot plant. This clone contains a 832 basepair insert which encodes the entire 120 amino acids of the mature small subunit polypeptide (Mr = 14,127). In addition this clone encodes 53 amino acids of the amino terminal transit peptide of the precursor polypeptide and 242 nucleotides of the 3' non-coding region. Comparison of the nucleotide sequence of pLgSSU with Lemna gibba genomic sequences homologous to the 5' end of the cDNA clone suggests that nucleotides encoding four amino-terminal amino acids of the transit peptide are not included in the cDNA clone. The deduced amino acid sequence of the Lemna gibba mature small subunit polypeptide shows 70-75% homology to the reported sequences of other species. The transit peptide amino acid sequence shows less homology to other species. There is 50% homology to the reported soybean sequence and only 25% homology to the transit sequence of another monocot, wheat.     

Tumor suppression in Drosophila is causally related to the function of the lethal(2)tumorous imaginal discs gene,a dnaJ homolog

The Drosophila melanogaster tumor suppressor gene lethal(2)tumorous imaginal discs (l(2)tid) causes in homozygotes malignant growth of cells of the imaginal discs and the death of the mutant larvae at the time of puparium formation. We describe the molecular cloning of the 1(2)tid+ gene and its temporal expression pattern in the wild-type and mutant alleles. Germ line rescue of the tumor phenotype was achieved with a 7.0 kb Hindlll-fragment derived from the polytene chromosome band 59F5. The l(2)tid+ gene spans approximately 2.5 kb of genomic DNA. The protein coding region, 1,696 bps long, is divided by an intron into two exons. The predicted Tid⁵⁶ protein contains 518 amino acids and possesses a theoretical molecular weight of 56 kDa. It shows significant homology to all known DnaJ related proteins from bacteria, yeast, and man. The possible function of the Tid⁵⁶ protein in tumor suppression is delineated. © 1995 Wiley-Liss, Inc.     

Expression during embryogenesis of a mouse gene with sequence homology to the Drosophila engrailed gene

Regions of the mouse and human genomes with strong homology to the Drosophila engrailed gene have been identified by Southern blot analysis. One mouse engrailed-like region, Mo-en.1, has been cloned and partially sequenced; homology with the engrailed gene is localized to a 180 bp engrailed-like homeo box and 63 nucleotides immediately 3' to it. The protein sequence this region can encode includes 81 amino acids, of which 60 (75%) are identical with those of the putative translation product of the corresponding engrailed sequence. These data suggest that Mo-en.1 represents a mouse homolog of a gene of the Drosophila engrailed gene complex. Mo-en.1 has been mapped to chromosome 1, indicating it is not linked to other homeo box sequences that have been mapped in the mouse genome. Analysis of poly(A)+ RNA extracted from teratocarcinoma cells and whole mouse embryos demonstrates that the conserved homeo box region of Mo-en.1 is expressed differentially during mouse embryogenesis.     

Cloning, expression, and chromosomal localization of the 140-kilodalton subunit of replication factor C from mice and humans.

We have isolated a full-length mouse cDNA encoding a lysine-rich protein of 1,131 amino acids with a calculated molecular mass of 126 kDa. The protein binds in a sequence-unspecific manner to DNA, is localized exclusively in the nucleus, and contains a putative ATP binding site and a stretch of 80 amino acids with homology to the carboxy terminus of prokaryotic DNA ligases. On the basis of the following facts, we conclude that the isolated cDNA encodes the 140-kDa subunit of mouse replication factor C (mRFC140). (i) The sequence around the ATP binding site shows significant homology to three small subunits of human replication factor C. (ii) Polyclonal antibodies raised against the protein encoded by this cDNA cross-react with the 140-kDa subunit of purified human replication factor C (hRFC140) and recognize in mouse cell extracts an authentic protein with an apparent molecular mass of 130 kDa. (iii) Sequence comparison with a human cDNA isolated by using tryptic peptide sequence information from purified hRFC140 revealed 83% identity of the encoded proteins. The mRFC140 gene is ubiquitously expressed, and two mRNAs approximately 5.0 and 4.5 kb long have been detected. The gene was mapped by in situ hybridization to mouse chromosome 5, and its human homolog was mapped to chromosome 4 (p13-p14).