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Collagen XVIII is a basement membrane heparan sulfate proteoglycan.

The present study shows that collagen XVIII is, next to perlecan and agrin, the third basal lamina heparan sulfate proteoglycan (HSPG) and the first collagen/proteoglycan with heparan sulfate side chains. By using monoclonal antibodies to an unidentified HSPG in chick, 14 cDNA clones were isolated from a chick yolk sac library. All clones had a common nucleotide sequence that was homologous to the mRNA sequences of mouse and human collagen XVIII. The deduced amino acid sequence of the chick fragment shows an 83% overall homology with the human and mouse collagen XVIII. Similar to the human and mouse homologue, the chick collagen XVIII mRNA has a size of 4.5 kilobase pairs. In Western blots, collagen XVIII appeared as a smear with a molecular mass of 300 kDa. After treatment with heparitinase, the protein was reduced in molecular mass by 120 kDa to a protein core of 180 kDa. Collagen XVIII has typical features of a collagen, such as its existence, under non-denaturing conditions, as a non-covalently linked oligomer, and a sensitivity of the core protein to collagenase digestion. It also has characteristics of an HSPG, such as long heparitinase-sensitive carbohydrate chains and a highly negative net charge. Collagen XVIII is abundant in basal laminae of the retina, epidermis, pia, cardiac and striated muscle, kidney, blood vessels, and lung. In situ hybridization showed that the main expression of collagen XVIII HSPG in the chick embryo is in the kidney and the peripheral nervous system. As a substrate, collagen XVIII moderately promoted the adhesion of Schwann cells but had no such activity on peripheral nervous system neurons and axons.

Amino Acid Sequence↗

Nucleotide sequences that signal the initiation of transcription and translation in Bacillus subtilis.

We have determined the nucleotide sequence of two Bacillus subtilis promoters (veg and tms) that are utilized by the principal form of B. subtilis RNA polymerase found in vegetative cells (sigma 55-RNA polymerase) and have compared our sequences to those of several previously reported Bacillus promoters. Hexanucleotide sequences centered approximately 35 (the "--35" region) and 10 (the "--10" region) base pairs upstream from the veg and tms transcription starting points (and separated by 17 base pairs) corresponded closely to the consensus hexanucleotides (TTGACA and TATAAT) attributed to Escherichia coli promoters. Conformity to the preferred --35 and --10 sequences may not be sufficient to promote efficient utilization by B. subtilis RNA polymerase, however, since three promoters (veg, tms and E. coli tac) that conform to these sequences and that are utilized efficiently by E. coli RNA polymerase were used with highly varied efficiencies by B. subtilis RNA polymerase. We have also analyzed mRNA sequences in DNA located downstream from eight B. subtilis chromosomal and phage promoters for nucleotide sequences that might signal the initiation of translation. In accordance with the rules of McLaughlin, Murray and Rabinowitz (1981), we observe mRNA nucleotide sequences with extensive complementarity to the 3' terminal region of B. subtilis 16S rRNA, followed by an initiation codon and an open reading frame.

Bacillus subtilis↗

Mutational analysis of upstream AUG codons of poliovirus RNA.

The 5' untranslated region of poliovirus type 2 Lansing RNA consists of 744 nucleotides containing seven AUG codons which are followed by in-frame termination codons, thus forming short open reading frames (ORFs). To determine the biological significance of these small ORFs, all of the upstream AUG codons were mutated to UUG. The point mutations were introduced into an infectious poliovirus cDNA clone, and RNA transcribed in vitro from the altered cDNA was transfected into HeLa cells to recover the virus. Mutation of AUG 7 resulted in a virus (called R2-5NC-14) with a small-plaque phenotype, whereas mutation of the other six AUG codons produced virus with a wild-type plaque morphology. To determine whether the small-plaque phenotype of R2-5NC-14 was due to altered translational efficiency of the viral mRNA, we constructed chimeric mRNAs containing the 5' noncoding region of poliovirus mRNA fused to the chloramphenicol acetyltransferase (CAT) coding sequence. mRNA containing a mutated AUG 7 codon showed decreased translational efficiency in vitro. The results indicate that the upstream ORFs of poliovirus RNA are not essential for viral replication and do not act as barriers to the translation of poliovirus mRNA. AUG 7 and flanking sequences may play a positive acting role in poliovirus RNA translation.

Codon↗

Rat ligandin mRNA molecular cloning and sequencing.

Recombinant plasmids containing the double-stranded cDNA sequences of mRNA for the Mr 22,000 ligandin (glutathione S-transferase B) subunit (Ya) have been constructed. The DNA sequence of an insert corresponding to the middle and 3' regions of the mRNA was determined and an amino acid sequence was proposed for the ligandin Ya subunit. The proposed sequence reveals a high content of basic amino acids (Arg and Lys) and Leu, is consistent with the amino acid composition, and predicts the correct number of peptides derived from tryptic digests reported for ligandin.

Amino Acid Sequence↗

Sequence of chicken ovalbumin mRNA.

The complete sequence of chicken ovalbumin mRNA is presented; it is 1,859 residues long, excluding its terminal 'cap' and poly(A). The region coding for ovalbumin lies close to the 'cap' but is separated from the poly(A) by an extensive 3' noncoding region of 637 nucleotides which may have no function that is precisely dependent on its sequence.

Amino Acid Sequence↗

Alphafetoprotein messenger RNA in human embryonal carcinoma grown in nude mice, and cloning of its complementary DNA.

Messenger RNA for human apha-fetoprotein (AFP) was partially purified from human testicular embryonal carcinoma grown in nude mice. DNA complementary to the mRNA was synthesized, tailed with oligo(dC) and inserted at the PstI site of the plasmid pBR322 tailed with oligo(dG). Escherichia coli strain LE392 was transformed with the chimeric plasmid and colonies were screened for human AFP mRNA sequences by hybridization with DNA complementary to mouse AFP mRNA (greater than 95% pure). Five colonies showed positive hybridization. The plasmid pHAF2, containing the largest insert, 900 nucleotides, was further characterized by hybrid-arrest of translation of AFP mRNA, restriction endonuclease mapping and partial nucleotide sequence analysis. It was found that the AFP complementary DNA (cDNA) sequence in pHAF2 corresponded to the 3'-end of AFP messenger RNA (mRNA), and showed a restriction map entirely different from that of mouse AFP cDNA clones previously reported.

Animals↗

A G-to-A mutation in IVS-3 of the human gamma fibrinogen gene causing afibrinogenemia due to abnormal RNA splicing.

Congenital afibrinogenemia is a rare autosomal recessive disorder characterized by a hemorrhagic diathesis of variable severity. Although more than 100 families with this disorder have been described, genetic defects have been characterized in few cases. An investigation of a young propositus, offspring of a consanguineous marriage, with undetectable levels of functional and quantitative fibrinogen, was conducted. Sequence analysis of the fibrinogen genes showed a homozygous G-to-A mutation at the fifth nucleotide (nt 2395) of the third intervening sequence (IVS) of the gamma-chain gene. Her first-degree relatives, who had approximately half the normal fibrinogen values and showed concordance between functional and immunologic levels, were heterozygtes. The G-to-A change predicts the disappearance of a donor splice site. After transfection with a construct, containing either the wild-type or the mutated sequence, cells with the mutant construct showed an aberrant messenger RNA (mRNA), consistent with skipping of exon 3, but not the expected mRNA. Sequencing of the abnormal mRNA showed the complete absence of exon 3. Skipping of exon 3 predicts the deletion of amino acid sequence from residue 16 to residue 75 and shifting of reading frame at amino acid 76 with a premature stop codon within exon 4 at position 77. Thus, the truncated gamma-chain gene product would not interact with other chains to form the mature fibrinogen molecule. The current findings show that mutations within highly conserved IVS regions of fibrinogen genes could affect the efficiency of normal splicing, giving rise to congenital afibrinogenemia.

Afibrinogenemia↗

Interleukin-1-mediated stabilization of mouse KC mRNA depends on sequences in both 5'- and 3'-untranslated regions.

mRNA transcribed from the mouse KC chemokine gene accumulated to significantly higher levels in multiple cell types after treatment with interleukin 1alpha (IL-1alpha) as compared with tumor necrosis factor-alpha (TNFalpha). Although TNFalpha and IL-1alpha both signaled the activation of nuclear factor kappaB and enhanced transcription of the KC gene with equal potency, only IL-1alpha treatment resulted in stabilization of KC mRNA. Nucleotide sequences that confer sensitivity for IL-1alpha-mediated mRNA stabilization were identified within the 5'- and 3'-untranslated regions (UTRs) of KC mRNA using transient transfection of chimeric plasmids containing specific portions of KC mRNA linked to the chloramphenicol acetyltransferase (CAT) gene. When plasmids containing either the 3'- or 5'-UTR of KC mRNA were used, the half-life of CAT mRNA was unaltered either in untreated or IL-1alpha-stimulated cells. In contrast, CAT mRNA transcribed from plasmids that contained both the 5'- and 3'-UTRs of the KC mRNA decayed more rapidly than control CAT mRNA, and this enhanced decay was prevented in cells treated with IL-1alpha. A cluster of four overlapping AUUUA motifs within the 3'-UTR was required, whereas the 5'-UTR region exhibited orientation dependence. These findings indicate that cooperative function of the two nucleotide sequences involves a distinct signaling pathway used by IL-1alpha but not TNFalpha.

3' Untranslated Regions↗

The imported preprotein of the proteolipid subunit of the mitochondrial ATP synthase from Neurospora crassa. Molecular cloning and sequencing of the mRNA.

The proteolipid subunit of the mitochondrial ATP synthase from Neurospora crassa is an extremely hydrophobic protein of 81 amino acid residues, which is imported into mitochondria as a precursor of mol. wt. 15 000. The primary structure of the imported form has now been determined by isolating and analyzing cDNA clones of the preproteolipid mRNA. An initial cDNA clone was identified by hybridizing total polyadenylated RNA to pooled cDNA recombinant plasmids from an ordered clone bank and subsequent cell-free translation of hybridization-selected mRNA. Further preproteolipid clones were identified at a frequency of 0.2% by colony filter hybridization. One isolated cDNA represented the major part of the preproteolipid mRNA. The nucleotide sequence showed 243 bases corresponding to the mature proteolipid and, in addition, 178 bases coding for an amino-terminal presequence . Non-coding sequences of 48 bases at the 5' end and of 358 bases at the 3' end plus a poly(A) tail were determined. The long presequence of 66 amino acids is very polar, in contrast to the lipophilic mature proteolipid, and includes 12 basic and no acidic side chains. It is suggested that the presequence is specifically designed to solubilize the proteolipid for post-translational import into the mitochondria.

ATP Synthetase Complexes↗

Tissue-specific expression of porphobilinogen deaminase. Two isoenzymes from a single gene.

Porphobilinogen deaminase (hydroxymethylbilane synthase; EC 4.3.1.8), the third enzyme of the heme biosynthetic pathway, catalyzes the stepwise condensation of four porphobilinogen units to yield hydroxymethylbilane, which is in turn converted to uroporphyrinogen III by cosynthetase. We compared the apparent molecular mass of porphobilinogen deaminase from erythropoietic and from non-erythropoietic cells by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and immune-blotting. The results indicate that two isoforms of porphobilinogen deaminase can be distinguished and differ by 2000 Da. Analysis of cell-free translation products directed by mRNAs from human erythropoietic spleen and from human liver demonstrates that the two isoforms of porphobilinogen deaminase are encoded by distinct messenger RNAs. We cloned and sequenced cDNAs complementary to the non-erythropoietic form of porphobilinogen deaminase encoding RNA. Comparison of these sequences to that of human erythropoietic mRNA [Raich et al. (1986) Nucleic Acids Res. 14, 5955-5968] revealed that the two mRNA species differ by their 5' extremity. From the mRNA sequences we could deduce that an additional peptide of 17 amino acid residues at the NH2 terminus of the non-erythropoietic isoform of porphobilinogen deaminase accounts for its higher molecular mass. RNase mapping experiments demonstrate that the two porphobilinogen deaminase mRNAs are distributed according to a strict tissue-specificity, the erythropoietic form being restricted to erythropoietic cells. We propose that a single porphobilinogen deaminase gene is transcribed from two different promoters, yielding the two forms of porphobilinogen deaminase mRNAs. Our present finding may have some relevance for further understanding the porphobilinogen deaminase deficiency in certain cases of acute intermittent porphyria with an enzymatic defect restricted in non-erythropoietic cells.

Ammonia-Lyases↗

Multiple cDNA sequences and the evolution of bovine stomach lysozyme.

To investigate the origin of stomach expression of lysozyme in ruminants; we surveyed clones from a cow stomach cDNA library with a lysozyme cDNA probe. Ten percent of the clones in this library were lysozyme-specific. Thirty of the lysozyme clones were sequenced, and seven types of lysozyme mRNA sequence were found. They encode the three previously identified stomach isozymes of lysozyme. The seven sequences are closely related to one another and represent the products of a minimum of 4 of the approximately 10 cow lysozyme genes detected by genomic blotting. The most abundant form of stomach lysozyme (form 2) is encoded by at least two genes, whereas forms 1 and 3 are possibly each encoded by only one gene. The number of genes encoding each isozyme appears to contribute the largest factor in the relative abundance of each isozyme. The multiple lysozyme genes expressed in the cow stomach are the result of gene duplications that occurred during ruminant evolution. The recruitment of lysozyme as a major enzyme in the stomach may thus have involved an early regulatory event and a later 4-7-fold increase in expression allowed by gene amplification. During this period, the amino acid sequences of these lysozymes have been evolving more slowly than those of nonruminant lysozymes.

Abomasum↗

The cDNA sequence coding for prepro-PGS (prepro-magainins) and aspects of the processing of this prepro-polypeptide.

Amphibian skin is well known as a source of peptides homologous to bioactive peptides found in mammalian gut and brain. A systematic investigation of the skin secretions from Xenopus laevis revealed several peptides not derivable from known precursors. The sequence elucidation, utilizing fast atom bombardment/mass spectrometry, of two peptides, PGS and PGS Gly-10;Lys-22, is reported. These have been independently characterized and named magainins and found to have antimicrobial activity. A mixed sequence oligonucleotide probe complementary to the mRNA sequence coding for PGS was synthesized and used to screen a Xenopus skin cDNA library. A full length cDNA species encoding prepro-PGS was isolated and characterized, and its sequence is reported. The deduced precursor sequence was found to contain one copy of PGS Gly-10;Lys-22 and five copies of PGS. The proteolytic processing of this prepro-polypeptide is discussed.

Amino Acid Sequence↗

Changes in polysomal polyadenylated RNA and alpha-fetoprotein messenger RNA during hepatocarcinogenesis.

Polysomal polyadenylated RNA was isolated from preneoplastic and neoplastic livers obtained from rats kept on a choline-deficient diet containing ethionine for 8 and 25 to 32 weeks, respectively. Normal, preneoplastic, and neoplastic liver polysomal messenger RNA's (mRNA's) were hybridized with homologous and heterologous 3H-labeled complementary DNA's (cDNA's). The results show that, in terms of RNA mass, all or most of the polysomal polyadenylated RNA present in preneoplastic or neoplastic liver is also present in normal liver. This was induced by the similar extent of hybridization between [3H]cDNA transcribed from preneoplastic or neoplastic liver mRNA's with their homologous mRNA's and with mRNA from normal liver. Conversely, most or all of the polysomal polyadenylated RNA of normal liver is also found in preneoplastic and neoplastic livers, as indicated by the extent of hybridization of [3H]cDNA transcribed from normal liver with mRNA's from normal, preneoplastic, and neoplastic livers. Shifts in the relative abundance of mRNA sequences were detected in the polysomal mRNA of preneoplastic livers and especially in the mRNA of neoplastic liver. Hybridization of alpha-fetoprotein cDNA with liver polyadenylated RNA showed a substantial increase in alpha-fetoprotein mRNA content after 8 and 15 weeks of feeding the carcinogenic diet. Similar experiments using globin cDNA failed to show an increase in globin mRNA content in preneoplastic livers.

Animals↗

Regulation of maternal messenger RNA translation during oogenesis and embryogenesis in Urechis caupo.

We have tested the hypothesis that the selective translation of mRNAs in oocytes and embryos is controlled by when during oogenesis individual maternal mRNAs are synthesized. In an earlier paper we described the isolation of cDNA probes to 21 maternal mRNAs which accumulate with different patterns during oogenesis in Urechis caupo (E. T. Rosenthal and F. H. Wilt, 1986, Dev. Biol. 117, 55-62). Many of these probes have now been used to analyze the translation of the maternal mRNAs in growing oocytes, full-grown oocytes, and embryos. The translation of all of the mRNAs studied changes dramatically when full-grown Urechis oocytes are fertilized. Our data do not support the idea that the translation of the different maternal mRNAs depends on when they were synthesized during oogenesis. This strongly suggests that, at some level, the ability of the cell's translational machinery to distinguish between different maternal mRNAs must reside directly, or indirectly, in the mRNA sequences. We have also found that in Urechis, as in Xenopus, the selective translation of maternal mRNAs is correlated with their selective adenylation. Consequently, we have sequenced the 3' ends of 16 translationally controlled maternal mRNAs in an effort to detect consensus sequences that might regulate adenylation. No such consensus sequences have been found, suggesting that the mRNA characteristics involved in the regulation of polyadenylation may reside in a wide variety of sequences or in more subtle features, such as secondary structure.

Animals↗

A 3' co-terminal family of mRNAs from the herpes simplex virus type 1 short region: two overlapping reading frames encode unrelated polypeptide one of which has highly reiterated amino acid sequence.

We have used DNA sequencing, mRNA mapping and in vitro translation to characterise three partially overlapping genes in the genome of herpes simplex virus (HSV) type 1. These genes specify three mRNAs with distinct 5' termini but a common 3' terminus, the longest of which is immediate-early (IE) mRNA-5. The 12,000 MW (12K) IE polypeptide encoded by IEmRNA-5 is translated from an 88 codon open reading frame, leaving a 1200 base 3' non-translated region. The second mRNA (mRNA-B) is initiated within the coding sequence of IEmRNA-5, and encodes a 21K polypeptide. The 12K and 21K polypeptide coding regions do not overlap. The third mRNA (mRNA-C) is initiated within the coding region of mRNA-B, and encodes a 33K polypeptide. The reading frame for 33K has a 110 codon out-of-frame overlap with the 21K reading frame. This is the first instance of overlapping genes described for HSV. The 21K polypeptide is thought to be a DNA binding protein and is remarkable for an array of 24 tandem repeats of the sequence X/Pro/Arg (where X represents predominantly Glu, Asp, Thr, Ser or Val) in its C-terminal portion. This array, which occupies most of the region of overlap with 33K, can vary in repeat number between virus strains.

Amino Acid Sequence↗

Ultraviolet and violet receptors express identical mRNA encoding an ultraviolet-absorbing opsin: identification and histological localization of two mRNAs encoding short-wavelength-absorbing opsins in the retina of the butterfly Papilio xuthus.

This paper describes the primary structures of two opsins of short-wavelength-absorbing visual pigments deduced from the mRNA sequences in the retina of the Japanese yellow swallowtail butterfly Papilio xuthus. A phylogenetic analysis of the amino acid sequences indicates that one of these visual pigments is of the ultraviolet-absorbing type and that the other is of the blue-absorbing type. We identified the photoreceptor cells that express these mRNAs by histological in situ hybridization. The mRNA of the ultraviolet type is expressed in two distinct photoreceptor types previously identified as ultraviolet and violet receptors, providing the first molecular biological evidence that different types of spectral receptor probably express a visual pigment with an identical amino acid sequence. The mRNA of the blue type is expressed exclusively in cells classified as blue receptors.

Amino Acid Sequence↗

TransTerm, the translational signal database, extended to include full coding sequences and untranslated regions.

TransTerm is a database of mRNA sequences and parameters useful for detecting translational control signals in general. TransTerm-98 has been expanded beyond previous years to include full coding sequences and UTRs, while retaining the original small contexts about the coding sequence start- and stop-codons. The database contains more than 130 000 non-redundant coding sequences with associated untranslated regions (UTRs) from over 450 species. This includes the complete genomes of 12 prokaryotic and one eukaryotic organism. Several coding sequence parameters are available: coding sequence length, Nc, GC3 and, when it is computable, Codon Adaptation Index (CAI). Codon usage tables and summaries of start- and stop-codon contexts are also included. TransTerm-98 has both a relational database form with a WWW interface and a flatfile format, also available by Internet browser. TransTerm is available at: http://biochem.otago.ac.nz:800/Transterm/homepage.h tml

Codon↗

A comparative analysis of prostate-specific antigen gene sequence in benign and malignant prostate tissue.

OBJECTIVES: Different molecular forms of prostate-specific antigen (PSA) appear to be expressed by benign prostatic hyperplasia (BPH) compared with prostate cancer. These differences are not well understood and may arise from aberrant RNA splicing, altered protein glycosylation, or variant PSA complexing to macroglobulins. To our knowledge, a direct comparison of PSA mRNA sequences in BPH versus prostate cancer to account for these differences has not been reported. The purpose of this study was to compare the complete PSA mRNA gene sequences in benign and malignant prostate tissue to determine whether altered PSA phenotypes are a result of gene mutations and to compare the published PSA sequences. METHODS: Total RNA was extracted from 17 prostate specimens from 8 patients, including matched benign and malignant prostate tissue in 6 patients. The samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) of the PSA coding sequence and part of the 3' untranslated region. Directed DNA sequencing was performed on these fragments. RESULTS: The benign and malignant prostate tissue cDNA sequence data of both strands were aligned and a computer analysis revealed 100% match with no evidence of mutation in prostate cancer compared to normal tissue. Sequence analysis did not reveal point mutations or aberrant splicing in any of the samples, including the matched malignant and nonmalignant tissues. Comparison with published sequences revealed infrequent and inconsistent sequence differences. CONCLUSIONS: These findings suggest that the PSA gene expressed in malignant prostate tissue is the wild type. PSA structural alterations previously reported in the literature may occur through post-transitional mechanisms. A detailed understanding of the possible differences in the PSA gene sequence is essential as we develop newer techniques that utilize RT-PCR to perform molecular diagnosis and staging of prostate cancer.

Base Sequence↗