The 5' noncoding and flanking regions of the avian very low density apolipoprotein II and serum albumin genes. Homologies with the egg white protein genes

Identification of five reptile egg whites protein using MALDI-TOF mass spectrometry and LC/MS-MS analysis

Proteomics of egg white proteins of five reptile species, namely Siamese crocodile (Crocodylus siamensis), soft-shelled turtle (Trionyx sinensis taiwanese), red-eared slider turtle (Trachemys scripta elegans), hawksbill turtle (Eretmochelys imbricate) and green turtle (Chelonia mydas) were studied by 2D-PAGE using IPG strip pH 4-7 size 7 cm and IPG strip pH 3-10 size 24 cm. The protein spots in the egg white of the five reptile species were identified by MALDI-TOF mass spectrometry and LC/MS-MS analysis. Sequence comparison with the database revealed that reptile egg white contained at least seven protein groups, such as serpine, transferrin precursor/iron binding protein, lysozyme C, teneurin-2 (fragment), interferon-induced GTP-binding protein Mx, succinate dehydrogenase iron-sulfur subunit and olfactory receptor 46. This report confirms that transferrin precursor/iron binding protein is the major component in reptile egg white. In egg white of Siamese crocodile, twenty isoforms of transferrin precursor were found. Iron binding protein was found in four species of turtle. In egg white of soft-shelled turtle, ten isoforms of lysozyme were found. Apart from well-known reptile egg white constituents, this study identified some reptile egg white proteins, such as the teneurin-2 (fragment), the interferon-induced GTP-binding protein Mx, the olfactory receptor 46 and the succinate dehydrogenase iron-sulfur subunit.

A highly efficient preparation of neoglycoconjugate vaccines using subcarriers that bear clustered carbohydrate antigens

A limited amount of spacer-equipped carbohydrate haptens was linked by reductive amination to a subcarrier, an oligopeptide containing 16 amino groups, to give a hapten-carrying subcarrier (HCS). It was then linked, via the remaining free amino groups, to chicken serum albumin (CSA) to give a cross-linked neoglycoconjugate bearing the haptens in the form of clusters. Alternatively, the same type of a glycoconjugate, but with higher conjugation efficiency, was obtained when HCS was treated successively with squaric acid diethyl ester and CSA.

Purification and partial amino acid sequences of two distinct albumins from turtle plasma

Two putative albumins, denoted Alb-1 (apparent molecular mass of 67 kDa) and Alb-2 (68 kDa), were purified from plasma of the emydid turtle (Trachemys scripta). Concentrations in serum or plasma were determined by radioimmunoassay using 125I-labeled Alb-1. In juvenile turtles (less than 2 years of age), serum concentrations of Alb-1 and Alb-2 were 2.72 +/- 0.23 mg/ml and 1.68 +/- 0.22 mg/ml, respectively, while concentrations in plasma pooled from adult turtles were 4.2 mg/ml and 2.6 mg/ml, respectively. The two albumins are immunologically distinct from one another as determined by both radioimmunoassay with 125I-labeled Alb-1 and Western blot analysis with antichicken albumin antiserum. Determination of the amino acid compositions of Alb-1 and Alb-2, and of albumin purified from plasma of the common snapping turtle (Chelydra serpentina), suggested that Alb-1 is more similar to albumins of other animals than is Alb-2. This was also indicated by Western blot analysis and by determining the N-terminal amino acid sequences of Alb-1 (40 residues) and Alb-2 (15 residues). Thus, it appears that two distinct forms of albumin are synthesized by T. scripta, possibly as a result of gene duplication and divergence.

Atlantic salmon (Salmo salar) serum albumin: cDNA sequence, evolution, and tissue expression

Atlantic salmon serum albumin is one of the most abundant proteins in salmon liver, representing 1.6% of all clones in a cDNA library made from salmon liver RNA. The DNA from a number of clones was sequenced to reveal an open reading frame of 1,827 bases encoding a 608-amino-acid protein. The sequenced 5' untranslated region is 69 bases long and the 3' untranslated region contains two putative polyadenylation signals and poly(A) tail. Sequence analysis of different clones indicates the presence of a second cDNA for salmon serum albumin. Multiple alignments of salmon serum albumin deduced amino acid sequence with Xenopus laevis, rat, bovine, and human serum albumins shows significant conservation of cysteine residues. The triple domain structure of serum albumin proteins is maintained. Unlike mammalian systems where serum albumin expression appears to be specific to liver only, salmon serum albumin is expressed in muscle also.

Nuclease sensitivity of estradiol-charged estrogen receptor binding sites in nuclei isolated from normal and neoplastic rat mammary tissues

The interaction of partially purified calf uterine estradiol-charged estrogen receptor ([3H]ER) with rat nuclei was studied in vitro. We previously observed a significantly greater number of [3H]ER binding sites (at saturation) in nuclei of R3230AC mammary tumors from intact vs ovariectomized (ovex) rats with no difference in the affinity of [3H]ER binding for these nuclei. We now report on the nuclease sensitivity of [3H]ER binding sites in nuclei from these tumors and from normal rat tissues. Digestion of tumor nuclei with deoxyribonuclease I (DNase I) prior to incubation with [3H]ER in vitro resulted in a progressive loss of [3H]ER binding capacity, which was not accompanied by alterations in the affinity of [3H]ER for the nuclei (Kd = 1-3 nM). A significantly lower concentration (P less than 0.005) of DNase I eliminated 50% of the [3H]ER binding sites in nuclei of tumors from intact hosts (8 unit.min/ml) compared to tumors from ovex hosts (22 unit.min/ml). These results indicate that DNA regions capable of binding ER are more susceptible to DNase I digestion in tumors from intact rats than those from ovex hosts, suggesting that the endogenous hormonal milieu is responsible, at least in part, for maintenance of nuclease-sensitive DNA conformations in this hormone-responsive mammary tumor. The amount of DNase I required to eliminate 50% of [3H]ER binding to nuclei from lactating mammary gland, liver, and kidney ranged from 14 to 56 unit.min/ml. Therefore, accessibility of [3H]ER binding sites to nuclease digestion in normal rat tissue is generally less than that of R3230AC tumors.

Identification of a calcium-dependent microsomal proteinase responsible for monobasic cleavage of chicken proalbumin

The location and nature of the endoproteolytic activity involved in processing of proproteins has been studied in chicken liver microsomes. A membrane-bound, calcium-dependent proteinase was found to cleave chicken proalbumin with a monobasic cleavage site approx. 10-times faster than human proalbumin, which has a dibasic cleavage site. The mutant (human) proalbumin Christchurch (Arg(-1)----Gln), with a potential monobasic site, was not processed. The enzyme, which had a pH optimum of between 5.0 and 7.0, was not inhibited by serine or aspartyl proteinase inhibitors but was affected by some inhibitors of cysteine proteinases. The convertase was specifically inhibited by the reactive centre variant alpha 1-antitrypsin Pittsburgh, but not by normal alpha 1-antitrypsin.

Differential effects of chromium(VI) on constitutive and inducible gene expression in chick embryo liver in vivo and correlation with chromium(VI)-induced DNA damage

The effect of DNA damage induced by the carcinogen chromium(VI) on the function of DNA as a template for transcription of constitutive and inducible genes was examined in chick embryo liver in vivo. Changes in gene expression, determined using solution hybridization and northern blot analyses to measure steady-state mRNA levels and a nuclear run-off assay to measure gene transcription rates, were compared to chromium-DNA binding and to chromium(VI)-induced DNA damage as previously measured by DNA alkaline elution. Chromium(VI) treatment had little or no effect on either the steady-state mRNA levels or the transcription rates of the constitutively expressed genes for albumin, conalbumin (avian transferrin), or beta-actin. In contrast, chromium(VI) treatment had significant but opposite effects on the basal and drug-inducible expression of 5-aminolevulinate synthase and cytochrome PB1 P450. The changes in steady-state expression of these two inducible genes were similar to the changes in transcription rate, indicating that the effects of chromium were principally transcriptional. Chromium(VI) treatment increased the basal expression of both inducible genes four- to fivefold at maximum, and the time course of this effect was similar to the time course for chromium(VI)-induced DNA damage and repair. In contrast, chromium(VI) pretreatment suppressed by 60-70% at maximum the subsequent induction of these genes by glutethimide, a phenobarbital analog, and the time course of this effect also corresponded to that of chromium(VI)-induced DNA damage and repair. The time courses of the changes in expression of these genes were bimodal, with the second peak corresponding closely to that of chromium(VI)-induced DNA cross-links. However, the first peak occurred during a period when no DNA cross-links or strand breaks were detectable by alkaline elution, although significant levels of chromium were bound to DNA. This suggests that chromium(VI), like cisplatin, may initially produce a DNA monoadduct that subsequently leads to DNA cross-link formation and that both types of chromium(VI)-induced lesions have a significant effect on the expression of targeted genes.

Estrogen-dependent activation of the avian very low density apolipoprotein II and vitellogenin genes. Transient alterations in mRNA polyadenylation and stability early during induction

Administration of estrogen to egg-laying vertebrates activates unscheduled, hepatic expression of major, egg-yolk protein genes in immature animals and mature males. Two avian yolk protein genes, encoding very low density apolipoprotein II (apoVLDLII) and vitellogenin II, are dormant prior to stimulation with estrogen, but within three days their cognate mRNAs accumulate to become two of the most abundant species in the liver. Accumulation of these mRNAs has been attributed to both induction of transcription and selective, estrogen-dependent mRNA stabilization. We have detected alterations in the size of apoVLDLII mRNA that occur during the first 24 hours that are attributable to a shift in the extent of polyadenylation as steady-state is approached. In vitro transcription assays indicate that primary activation of both genes takes place relatively slowly and that maximal rates of mRNA accumulation occur when the apoVLDLII and vitellogenin II genes are expressed at only 30% and 10% of their fully induced levels, respectively. Transcription data combined with the structural alteration of apoVLDLII mRNA suggest that stability of the two mRNAs may change as steady-state is approached. We have assessed the compatibility of this suggestion with earlier estimates of the kinetics of accumulation of both mRNAs by developing a generally useful algorithm that predicts approach to steady-state kinetics under conditions where both the rate of synthesis and mRNA stability change throughout the accumulation phase of the response. The results predict that the stability of both mRNAs decreases by at least two- to threefold during the approach to steady-state and that, although an additional destabilization of apoVLDLII mRNA may occur following withdrawal of estrogen, the steady-state stability of vitellogenin mRNA is not significantly decreased upon removal of hormone.

Hepatocyte-specific promoter element HP1 of the Xenopus albumin gene interacts with transcriptional factors of mammalian hepatocytes

By transfecting various Xenopus albumin-CAT fusion genes into the mouse hepatoma cell line BW1J a 13 base-pair hepatocyte-specific promoter element (HP1) could be identified. A similar sequence element is also present in the promoter of the albumin and alpha-fetoprotein genes of other vertebrates. Introduction of single point mutations into HP1 destroys its function. Binding studies with nuclear proteins identify a factor interacting with HP1 which is specific for hepatic cells. In-vitro transcription in a rat liver nuclear extract demonstrates that HP1 leads to an increased transcriptional activity. This increased transcription is specifically inhibited by the addition of an HP1-containing oligonucleotide, establishing that the interaction of factors with HP1 is essential for increased transcription. Since HP1 derived from a Xenopus gene functions in mammalian hepatocytes, we conclude that a regulatory system involved in liver-specific gene expression has been conserved during evolution.

Human Ia-associated invariant chain gene has multiple transcription initiation sites in CLL cells

We show a northern transfer experiment revealed two mRNA of Ia-associated invariant chain (In) gene in chronic lymphocytic leukemia (CLL) cells which are approximately 1580 and 1440 nucleotides in length. Primer extension experiment shows that less prominent transcript was found to initiate 140 nucleotides upstream from the major cap site. The newly identified cap site was preceded by CG rich sequence but no typical promotor sequence. Southern hybridization analysis with In cDNA probe indicates no recombination or amplification of In gene in the CLL cells. This is the first documented example of such a mode of expression in malignant cells in vivo.

5'-flanking and 5'-proximal exon regions of the two Xenopus albumin genes. Deletion analysis of constitutive promoter function

The 5'-flanking regions and the first two exons of the 68kd and 74kd albumin genes of Xenopus laevis reveal extensive sequence homology between the two in the exon part, in the 5'-flanking region up to position -400 as well as in the first intron. Sequence comparisons of the Xenopus genes with either the albumin genes of the chicken and mammals or the mammalian alpha-fetoprotein genes reveals no homology in the 5'-flanking region but some conserved features in the first exon. The analysis of the chromatin structure demonstrates a DNase I hypersensitive region in the promoter of the 68kd albumin gene specific for hepatocytes that express the albumin gene. Deletion analysis of albumin-CAT fusion genes indicates that a 69 base-pair fragment extending from -50 to +19 of the 68 kd albumin gene is sufficient for constitutive transcription in microinjected Xenopus oocytes. The addition of 5'-flanking sequences did not change the transcriptional activity. This is consistent with the sequence data that revealed no other promoter element in this region other than the TATA box. The absence of a CCAAT box distinguishes the Xenopus albumin genes from the mammalian albumin genes but is in agreement with the promoter structure of the alpha-fetoprotein genes.

Factors involved in control of tissue-specific expression of albumin gene

Elements controlling tissue-specific expression of the rat albumin gene reside within roughly 150 bp upstream of the transcriptional initiation site. We show here by DNAase I footprinting assays that at least four distinct factors present in extracts derived from cells expressing albumin interact with these sequences. One of these factors is closely related or identical to nuclear factor 1 (NF1). Extracts from nonhepatic tissues or from dedifferentiated hepatoma cells that do not transcribe the albumin gene display a different pattern of DNA-protein interactions. Mixing experiments show that the variant pattern of dedifferentiated cells is dominant over that of differentiated ones, suggesting that nonexpressing cells contain dominant negatively acting factors.

Molecular biology of parathyroid hormone

The entire biosynthetic pathway of PTH has been elucidated from the determination of the chromosomal location to the eventual secretion of the hormone from the cell. The human gene is present on the short arm of chromosome 11, and restriction site polymorphisms near the gene have been detected. The PTH genes and cDNAs have been isolated and characterized in the bovine, human, and rat species. The gene contains two introns, which are in the same position in each species, and dissect the gene into 3 exons that code, respectively, for the 5' untranslated region, the signal peptide, and PTH plus the 3' untranslated region. The mRNAs are about twice as long as necessary to code for preProPTH and contain a 7-methylquanosine cap at the 5' terminus and polyadenylic acid at the 3' terminus. The 5' termini of the bovine and human mRNAs are heterogeneous at the 5' terminus, the basis of which is two TATA sequences in the 5' flanking regions of the gene. In contrast, the rat gene contains a single TATA sequence and the mRNA has a single 5' terminus. The initial translational product of the mRNA is preProPTH, and the pre-peptide of 25 amino acids is equivalent to signal peptides of other secreted and membrane proteins. The genes of the three species are very homologous in the region that codes for preProPTH. Substantial homology is also retained in the gene flanking regions, introns, and mRNA untranslated regions. Silent sites are also conserved more than would be expected, particularly between the human and bovine sequences. The bovine and human sequences are more closely related than the rat is to either the human or bovine. These studies of the basic molecular biology of PTH will provide the framework for future analysis of significant biological and medical questions. In vitro mutagenesis techniques should soon provide information about the elements of the gene involved in regulating transcription and about functional elements of the signal peptide. Eventually, signals involved in directing the ProPTH molecule to secretory granules as well as the biologically active regions of PTH, itself, will be examined by these methods. The molecular biological studies, combined with the development of dispersed cell cultures, provide the opportunity to study the effects of chronic changes in calcium on gene transcription and mRNA metabolism. The restriction site polymorphisms associated with the human PTH gene will allow a search for correlations between PTH gene structure and parathyroid disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Eukaryotic RNA polymerases

This review will attempt to cover the present information on the multiple forms of eukaryotic DNA-dependent RNA polymerases, both at the structural and functional level. Nuclear RNA polymerases constitute a group of three large multimeric enzymes, each with a different and complex subunit structure and distinct specificity. The review will include a detailed description of their molecular structure. The current approaches to elucidate subunit function via chemical modification, phosphorylation, enzyme reconstitution, immunological studies, and mutant analysis will be described. In vitro reconstituted systems are available for the accurate transcription of cloned genes coding for rRNA, tRNA, 5 SRNA, and mRNA. These systems will be described with special attention to the cellular factors required for specific transcription. A section on future prospects will address questions concerning the significance of the complex subunit structure of the nuclear enzymes; the organization and regulation of the gene coding for RNA polymerase subunits; the obtention of mutants affected at the level of factors, or RNA polymerases; the mechanism of template recognition by factors and RNA polymerase.

Isolation and complete nucleotide sequence of the gene for bovine parathyroid hormone

The structure of the bovine parathyroid hormone (PTH) gene has been analyzed by Southern blot hybridization of genomic DNA and by nucleotide sequence analysis of a cloned PTH gene. In the Southern analysis, several restriction enzymes produced single fragments that hybridized to PTH cDNA suggesting that there is a single bovine PTH gene. The restriction map of the cloned gene is the same as that determined by Southern blot analysis of bovine DNA. The sequence of 3154 bp of the cloned gene has been determined including 510 bp and 139 bp in the 5' and 3' flanking regions, respectively. The gene contains two introns which separate three exons that code primarily for: (i) the 5' untranslated region, (ii) the pre-sequence of preProPTH, and (iii) PTH and the 3' untranslated region. The gene contains 68% A + T and unusually long stretches of 100- to 150-bp sequences containing alternating A and T nucleotides in the 5' flanking region and intron A. The 5' flanking region contains two TATA sequences, both of which appear to be functional as determined by S1 nuclease mapping. Compared to the rat and human genes, the locations of the introns are identical but the sizes differ. Comparable human and bovine sequences in the flanking regions and introns are about 80% homologous.