Isolation and characterization of human TR3 receptor: a member of steroid receptor superfamily

Complementary DNAs (cDNAs) encoding a member of steroid receptor super-family, named TR3 receptor, were isolated from a human prostate lambda gt11 cDNA library on the basis of homology of oligonucleotide probes to the DNA-binding domain common to members of the steroid receptor super-family. Expression of TR3 receptor cDNA produced a 64 kDa DNA-binding protein in a rabbit reticulocyte lysate. Nucleotide sequence analysis showed that TR3 receptor cDNA contains two regions of sequences which correspond to the DNA- and hormone-binding domains of members of the steroid receptor super-family. The amino acid sequences in the hormone-binding domain of the TR3 receptor shares about 20% homology with estrogen receptor and less than 15% homology with other known steroid receptors. The DNA-binding domain of the TR3 receptor has about 55% homology with all other known steroid receptors. TR3 receptor had 86% nucleotide and 91% amino acid sequence homology with mouse NUR/77, suggesting that TR3 receptor may be a human homologue of mouse NUR/77 gene product.     

Hamster estrogen receptor cDNA: cloning and mRNA expression

Estrogen-induced hamster kidney tumor model serves as a useful model to study the biochemical and molecular mechanisms of hormonal carcinogenesis. In this model, we have demonstrated an increased expression of estrogen receptor mRNA and protein in estrogen-treated kidneys and in estrogen-induced tumors. The sequence information for hamster estrogen receptor gene is not known and has been investigated in this study. A hamster uterus cDNA library was constructed and the 5'-region of the hamster estrogen receptor cDNA cloned from this library using polymerase chain reaction (PCR) methodology. Additionally, hamster kidney polyadenylated RNA was reverse transcribed and PCR amplified using primers that were designed based on maximum homology between mouse, rat and human estrogen receptor cDNAs. These PCR amplified fragments were cloned into plasmid vectors and clones with the expected size of the insert subjected to Southern blot analysis using human estrogen receptor cDNA as a probe. The positive clones on Southern blot analysis and the PCR amplified products from these clones were subjected to DNA sequence analysis. Using this strategy, a full length, 1978 bp hamster estrogen receptor cDNA has been cloned which shows 87% homology with human, 90% with rat and 91% with mouse estrogen receptor cDNA. The deduced amino acid shares 88% homology with human, and 93% with rat and mouse estrogen receptors. Hamster estrogen receptor domain C (DNA binding domain) shows a 100% homology with a similar domain from mouse, rat, human, pig, sheep, horse and chicken estrogen receptor (Genebank reference ID: AF 181077).     

Isolation and sequence analysis of a full-length cDNA for human M creatine kinase

A full length cDNA for human M creatine kinase has been isolated and sequenced. The cDNA contains 77 bp of 5' untranslated, 338 bp of 3' untranslated sequence and the entire coding region (1146 bp) for human M creatine kinase. The M creatine kinases from different species share considerable sequence homology within the coding region (77-91%) and in amino acid sequence (82-97%). Little or no sequence homology is observed in the 3' untranslated sequence of the mammalian M creatine kinases, although canine and human creatine kinase share overall 80% sequence homology in 5' untranslated sequence. A unique 8 bp sequence was identified in the 5' untranslated regions of mammalian M creatine kinase but is not present in B creatine kinase cDNA. The degree of sequence conservation observed implies an evolutionary constraint on M creatine kinase structure beyond that which would be expected for the maintenance of enzymatic function.     

An analysis by restriction enzymes of the genomic structure of the 3' untranslated region of the human estrogen receptor gene

The estrogen receptor gene has a very long 3' untranslated region. As a first step towards the analysis of this structural feature for any functional role, we have cloned the human genomic estrogen receptor gene. Extensive restriction enzyme analysis of this DNA and comparison of the sizes of the DNA fragments obtained with those predicted from published cDNA sequences indicate that the 3' exon extends for at least 4304 bases from base number 2018 in the cDNA to the end of the cDNA. The data also show that the most 3' intron in this gene occurs between bases 1902 and 2018 of the cDNA.     

Molecular cloning, sequencing and restriction mapping of the genomic sequence encoding human proacrosin.

In the present study, molecular cloning, sequencing and restriction mapping of the genomic sequence encoding human proacrosin is described. The full-length cDNA encoding human proacrosin was utilized to recover a 17-kb human genomic clone which was sequenced without further subcloning. The nucleotide sequences of the exons agree with the sequence of the cDNA reported previously. More than 500 bases of the promoter region were sequenced and found to be highly GC rich but devoid of an identifiable TATA box. These findings are generally consistent with a recently published report [Keime, S., Adham, I. M. & Engel, W. (1990) Eur. J. Biochem. 190, 195-200]. However, further sequence analysis revealed discrepancies between our clone and that previously reported. Sequencing of the first intron showed similarity with the published data for 54 bases of the 5' region, beginning with the donor splice site, and for 114 bases at the 3' end. However, 500 bases sequenced distal to the initial 54 bases at the 5' end of intron 1 showed no similarity with the published sequence. In addition, the boundaries of intron 3 differed such that a cytosine residue previously reported to be in exon 3 was found to be the first base of exon 4. Detailed studies were undertaken to confirm that our clone constitutes the authentic sequence of human proacrosin. Cloning and characterization of the human proacrosin gene may allow for informative studies of its regulation, and for a more detailed examination of its role in fertilization.     

Isolation and characterization of related cDNA clones encoding skeletal muscle beta-tropomyosin and a low-molecular-weight nonmuscle tropomyosin isoform.

We have isolated and characterized cDNA clones from chicken cDNA libraries derived from skeletal muscle, body wall, and cultured fibroblasts. A clone isolated from a skeletal muscle cDNA library contains the complete protein-coding sequence of the 284-amino-acid skeletal muscle beta-tropomyosin together with 72 bases of 5' untranslated sequence and nearly the entire 3' untranslated region (about 660 bases), lacking only the last 4 bases and the poly(A) tail. A second clone, isolated from the fibroblast cDNA library, contains the complete protein-coding sequence of a 248-amino-acid fibroblast tropomyosin together with 77 bases of 5' untranslated sequence and 235 bases of 3' untranslated sequence through the poly(A) tract. The derived amino acid sequence from this clone exhibits only 82% homology with rat fibroblast tropomyosin 4 and 80% homology with human fibroblast tropomyosin TM30nm, indicating that this clone encodes a third 248-amino-acid tropomyosin isoform class. The protein product of this mRNA is fibroblast tropomyosin 3b, one of two low-molecular-weight isoforms expressed in chicken fibroblast cultures. Comparing the sequences of the skeletal muscle and fibroblast cDNAs with a previously characterized clone which encodes the smooth muscle alpha-tropomyosin reveals two regions of absolute homology, suggesting that these three clones were derived from the same gene by alternative RNA splicing.     

Identification by sequence analysis of a second rat brain cDNA encoding the dopamine (D2) receptor

A rat brain cDNA library constructed in lambda ZAP II was screened with three oligonucleotide probes based on the reported coding region of the D2 receptor gene, RGB-2. A complete cDNA clone, D2(8)-1, showing positive signals with the three probes was subsequently identified by restriction analysis and dideoxy sequence analysis to be a variant of the RGB-2 gene. Comparison of the two genes revealed almost complete homology except that D2(8)-1 contains an 87 bp insert within the protein coding region and 265 additional nucleotides 5' upstream from the 5' end reported for RGB-2. It is suggested that at least two mRNA species encoding for D2 receptors exist in rat brain, possibly resulting from alternative splicing of RNA.     

Analysis of the regions flanking the human insulin gene and sequence of an Alu family member.

The regions around the human insulin gene have been studied by heteroduplex, hybridization and sequence analysis. These studies indicated that there is a region of heterogeneous length located approximately 700 bp before the 5' end of the gene; and that the 19 kb of cloned DNA which includes the 1430 bp insulin gene as well as 5650 bp before and 11,500 bp after the gene is single copy sequence except for 500 bp located 6000 bp from the 3' end of the gene. This 500 bp segment contains a member of the Alu family of dispersed middle repetitive sequences as well as another less highly repeated homopolymeric segment. The sequence of this region was determined. This Alu repeat is bordered by 19 bp direct repeats and also contains an 83 bp sequence which is present twice. The regions flanking the human and rat I insulin genes were compared by heteroduplex analysis to localize homologous sequences in the flanking regions which could be involved in the regulation of insulin biosynthesis. The homology between the two genes is restricted to the region encoding preproinsulin and a short region of approximately 60 bp flanking the 5' side of the genes.     

The human insulin receptor cDNA: the structural basis for hormone-activated transmembrane signalling

A cloned approximately 5 kb cDNA (human placenta) contains the coding sequences for the insulin receptor. The nucleotide sequence predicts a 1382 amino acid precursor. The alpha subunit comprises the N-terminal portion of the precursor and contains a striking cysteine-rich "cross-linking" domain. The beta-subunit (the C-terminal portion of the precursor) contains a transmembrane domain and, in the intracellular region, the elements of a tyrosine phosphokinase: an ATP-binding site and a possible tyrosine autophosphorylation site or sites. The overall structure is reminiscent of the EGF receptor; the cross-linking domain of the alpha subunit and several regions of the beta subunit exhibit sequence homology with the EGF receptor. The phosphokinase domain also exhibits homology with some oncogenic proteins that have tyrosine phosphokinase activity, in particular, a striking homology with v-ros. Southern blotting experiments suggest that the coding region spans more than 45 kb. The insulin receptor gene is located on chromosome 19.     

Molecular cloning of a steroid-regulated 108K heat shock protein gene from hen oviduct.

The natural gene for a steroid inducible 108K heat shock protein has been isolated from a lambda genomic library prepared from hen oviduct tissue. Genomic DNA blots indicate that it exists as a single copy gene in the chick oviduct haploid genome. The 9.9 kilobase gene codes for a messenger RNA of 2733bp (21) and is split into 18 exons as established by sequence comparison of cDNA and genomic clones. The 3' end of the gene contains a repetitive element which shares homology with the CR1 family of repeats. The first exon contains both the untranslated leader and coding regions of the gene. The promoter region is rich in G + C residues (70%) and the dinucleotide CG. This 5' flanking segment contains bases similar both in sequence and location to the Goldberg-Hogness TATA homology and consensus sequence CCAAT. A consensus sequence located upstream of steroid hormone responsive chicken genes is found at -267 and on a reverse orientation at -593. The structure of this gene is of interest since the presence of introns in heat shock genes is rare in any species examined to date. Furthermore, this gene lacks the previously described heat shock promoter consensus sequence (C-GAA-TTC-G) present in other species.     

Nucleotide sequence of a full-length complementary DNA clone and amino acid sequence of human phenylalanine hydroxylase

A full-length human phenylalanine hydroxylase complementary DNA (cDNA) clone was isolated from a human liver cDNA library, and the nucleotide sequence encoding the entire enzyme was determined. The cDNA clone contains an inserted DNA fragment of 2448 base pairs, including 19 base pairs of poly(A) at the 3' end. The first methionine codon occurs at nucleotide position 223, followed by an open reading frame of 1353 base pairs, encoding 451 amino acids. Translation of the nucleotide sequence in the open reading frame predicts the amino acid sequence of human phenylalanine hydroxylase. The human protein shows a 96% amino acid sequence homology with the corresponding rat enzyme. The determination of the complete primary structure for phenylalanine hydroxylase represents the first among mixed-function oxidases.     

Cloning of a Drosophila cDNA encoding a polypeptide similar to the human insulin receptor precursor

A Drosophila cDNA clone was obtained using the human insulin receptor cDNA sequence as a probe. The 3586 bp nucleotide sequence predicted a single polypeptide of 1095 amino acid residues which showed considerable homology (35.2%) with the human insulin receptor precursor. Although the cDNA was incomplete at its 5'-terminal region, it encodes a transmembrane glycoprotein as a single precursor of a two subunit molecule having a structural architecture similar to that of the human insulin receptor precursor. The presumptive beta subunit carries a well conserved Tyr kinase domain which showed 63.5% homology with that of human insulin receptor; however the protein of the alpha subunit is only weakly conserved (25%).