The end of the message: 3'-end processing leading to polyadenylated messenger RNA

Molecular flexibility and discontinuous translocation of a non-templated polymerase

Little is known regarding the translocation of non-templated nucleic acid polymerases with respect to single-stranded primers. VP55, the vaccinia virus poly(A) polymerase, translocates as it processively adds a approximately 3-7 adenylate tail to primers possessing only three ribouridylate residues (as an (rU)(2)-N(15)-rU motif), and a approximately 25-30 adenylate tail to primers that are more U-rich. Here, three models were addressed for the translocation of VP55 with respect to its primer, namely: (a) rigid protein/rigid nucleic acid; (b) flexible protein/rigid nucleic acid; (c) rigid protein/flexible nucleic acid. Analysis of free and covalently VP55-attached primers favored either (b) or a version of (c) incorporating a passive steric block, and suggested two regions of relative motion between polymerase and primer. Inclusion of a 6nt uridylate-rich patch at the primer 3' end switched the polymerase from approximately 3-7 nt to approximately 25-30 nt tail addition without affecting initial binding affinity. By synthesizing this patch as a (rU/dC) pool, discontinuous polymerase movements could be detected.

Amino acid sequence and structure modeling of savignin, a thrombin inhibitor from the tick, Ornithodoros savignyi

The full-length gene of savignin, a potent thrombin (E.C. 3.4.21.5) inhibitor from the tick Ornithodoros savignyi has been cloned and sequenced. Both 5' and 3' UTR's, a signal peptide from the translated amino acid sequence and an unusual poly-adenylation signal (AATACA) has been identified. The translated protein sequence shows high identity (63%) with ornithodorin, the thrombin inhibitor from the tick, Ornithodoros moubata. Molecular modeling using the structure of ornithodorin as reference gave a structure with an RMSD of 0.25 A for the full-length protein, 0.11 A for the N-terminal BPTI-like domain and 0.11 A for the C-terminal BPTI-like domain, indicating that maximum deviation occurs in the mobile bridge (0.18 A) between the two domains. Docking of savignin to thrombin shows that the interaction is similar to the ornithodorin-thrombin complex. The N-terminal amino acid residues of savignin bind inside the active site cleft, while the C-terminal domain of savignin has a net negative electrostatic potential and interacts with the basic fibrinogen recognition exosite of thrombin through hydrogen bonds and hydrophobic interactions. These results correlate with kinetic data obtained, which showed that savignin is a competitive, slow, tight-binding inhibitor that requires thrombin's fibrinogen-binding exo-site for optimal inhibition.

Isolation and characterization of two novel forms of the human prolactin receptor generated by alternative splicing of a newly identified exon 11

We have identified a novel exon 11 of the human prolactin receptor (hPRLR) gene that is distinct from its rodent counterparts and have demonstrated the presence of two novel short forms of the hPRLR (S1(a) and S1(b)), which are derived from alternative splicing of exons 10 and 11. S1(a) encodes 376 amino acids (aa) that contain partial exon 10 and a unique 39-aa C-terminal region encoded by exon 11. S1(b) encodes 288 aa that lack the entire exon 10 and contains 3 amino acids at the C terminus derived from exon 11 using a shifted reading frame. These short forms, which were found in several normal tissues and in breast cancer cell lines, were expressed as cell surface receptors and possessed binding affinities comparable with the long form. Unlike the long form, neither short form was able to mediate the activation of the beta-casein gene promoter induced by prolactin. Instead they acted as dominant negative forms when co-expressed with the long form in transfected cells. Due to a marked difference in the cellular levels between the two short forms in transfected cells, S1(b) was more effective in inhibiting the prolactin-induced activation of the beta-casein gene promoter mediated by the long form of the receptor. The low cellular level of S1(a) was due to its more rapid turnover than the S1(b) protein. This is attributable to specific residues within the C-terminal unique 39 amino acids of the S1(a) form and may represent a new mechanism by which the hPRLR is modulated at the post-translational level. Since both short forms contain abbreviated cytoplasmic domains with unique C termini, they may also exhibit distinct signaling pathways in addition to modulating the signaling from the long form of the receptor. These receptors may therefore play important roles in the diversified actions of prolactin in human tissues.

Xenopus adenine nucleotide translocase mRNA exhibits specific and dynamic patterns of expression during development

We report the isolation and characterization of the Xenopus homolog to human T1 ANT (adenine nucleotide translocase). The 1290-nucleotide sequence contains initiation and termination signals, and encodes a conceptual protein of 298 amino acids. The sequence shares high amino acid identity with the mammalian adenine translocases. The transcript is present in unfertilized eggs, and it is expressed at higher levels during formation of the antero-posterior dorsal axis in embryos. Although low levels are expressed constitutively except in endodermal cells, adenine nucleotide translocase (ANT) expression is dynamically regulated during neurulation. At this stage, expression in ectoderm rapidly diminishes as the neural folds form, and then ANT expression increases slightly in mesoderm. At the culmination of neurulation, the neural tube briefly expresses ANT, and thereafter its expression predominates in the somitic mesoderm and also the chordoneural hinge. In addition, ANT expression is particularly high in the prosencephalon, the mesencephalon, the branchial arches, eye, and the otic vesicle. Treatment of embryos with retinoic acid has the effect of diminishing constitutive expression of ANT, but microinjection studies demonstrate that immediate and local repression cannot be induced in dorsal structures.Key words: adenine nucleotide translocase, Xenopus, retinoic acid, pattern formation, gastrulation.

Human eIF5A2 on chromosome 3q25-q27 is a phylogenetically conserved vertebrate variant of eukaryotic translation initiation factor 5A with tissue-specific expression

Eukaryotic translation initiation factor 5A (eIF5A) is an essential protein tightly linked to cellular polyamine homeostasis. It receives the unique spermidine-derived posttranslational modification hypusine that is necessary for eIF5A's biochemical activity and cellular proliferation. The eIF5A protein stimulates ribosomal peptidyl-transferase and may be involved in nucleocytoplasmic mRNA transport. Little is known about the molecular genetics of eIF5A. Here we report on the sequence and molecular characterization of human EIF5A2, a novel phylogenetically conserved gene for eIF5A. EIF5A2 stretches over 17 kb and consists of five exons and four introns. It is localized at 3q25-q27, often noted for chromosomal instability in cancers. EIF5A2 is highly expressed in testis and colorectal adenocarcinoma and at moderate levels in the brain, in contrast to the ubiquitously expressed EIF5A1 gene. Two EIF5A2 mRNAs share a 129-nt 5' UTR and a coding sequence for the 153-amino-acid eIF5AII protein, but possess two alternative 3' UTRs of 46 and 890 nt that arise through differential polyadenylation. The protein is 84% identical and 94% similar to eIF5AI. Both EIF5A genes are conserved in vertebrates. Our findings lend further support for a specialized gene expression program of polyamine metabolic proteins and regulators that function to maintain polyamine homeostasis at elevated levels during spermatogenesis.

The structure of the gene for murine CTP:phosphocholine cytidylyltransferase, Ctpct. Relationship of exon structure to functional domains and identification of transcriptional start sites and potential upstream regulatory elements

Phosphatidylcholine (PC) is the most abundant eukaryotic phospholipid and serves critical structural and cell-signaling functions. CTP:phosphocholine cytidylyltransferase (CT) is the rate-limiting enzyme in the CDP-choline pathway of PC biosynthesis, which is utilized by all tissues and is the sole or major PC biosynthetic pathway in all non-hepatic cells. Herein, we present the complete structure of the murine CT (Ctpct) gene. One P1 genomic clone and six subsequent plasmid subclones were isolated and analyzed for the exon-intron organization of the Ctpct gene. The gene spans approximately 26 kilobases and is composed of 9 exons and 8 introns. The exons match the distinct functional domains of the CT enzyme: exon 1 is untranslated; exon 2 codes for the nuclear localization signal domain; exons 4-7 encompass the catalytic domain; exon 8 codes for the alpha-helical membrane-binding domain; and exon 9 includes the C-terminal phosphorylation domain. Two transcriptional initiation sites, spaced 35 nucleotides apart, were identified using 5'-rapid amplification of cDNA ends polymerase chain reaction. The 5' natural flanking region was found to lack TATA or CAAT boxes and to contain GC-rich regions, which are features typical of promoters of housekeeping genes. Several sites that have the potential to interact with transcription regulatory factors, such as Sp1, AP1, AP2, AP3, Y1, and TFIIIA, were identified in the 5'-region of the gene and found to be distributed in two distinct clusters. These data will provide the basis for future studies on the cis- and trans-acting factors involved in Ctpct gene transcription and for the creation of induced mutant mouse models of altered CT activity.

Identification of nuclear and cytoplasmic proteins that interact specifically with an AU-rich, cis-acting inhibitory sequence in the 3' untranslated region of human papillomavirus type 1 late mRNAs

Expression of human papillomavirus late genes encoding L1 and L2 capsid proteins is restricted to terminally differentiated epithelial cells. We have previously identified and characterized an AU-rich, cis-acting negative regulatory element in the 3' untranslated region of human papillomavirus type 1 late mRNAs. This element acts posttranscriptionally to reduce mRNA levels and the translation efficiency of mRNAs. The experiments reported here are a continuation of our previous work. We have used RNA gel shifts and UV cross-linking assays to identify cellular proteins that interact with the inhibitory RNA sequence of human papillomavirus type 1. RNA gel shift assays established that cellular proteins interact with the AU-rich sequence. The binding of nuclear proteins was inhibited by competition with poly(U), whereas the binding of cytoplasmic proteins was inhibited by competition with poly(U) and also by competition with poly(A) and poly(G). Two nuclear proteins and two cytoplasmic proteins that bind specifically to the AU-rich RNA sequence were identified by UV cross-linking. These proteins did not bind to the 3' untranslated region of human papillomavirus type 1 early mRNAs, which does not show inhibitory activity. The cellular proteins identified in our experiments may therefore be involved in the inhibition of human papillomavirus type 1 late gene expression in nondifferentiated epithelial cells.

Regulation of gene expression for translation initiation factor eIF-2 alpha: importance of the 3' untranslated region

Gene expression of the alpha-subunit of eukaryotic initiation factor-2 (eIF-2 alpha), involves transcriptional and post-transcriptional mechanisms. eIF-2 alpha is a single-copy gene expressing two mRNAs, 1.6 and 4.2 kb in size. Cloning and sequencing of the cDNA for the 4.2 kb mRNA revealed that it is the result of alternative polyadenylation site selection. Four polyadenylation sites were identified within the 3' untranslated region (UTR) of eIF-2 alpha, only two of which are normally utilized in human and mouse tissues. A functional role for the extended 3' UTR was assessed by comparing the translatability and stability of the 1.6 and 4.2 kb mRNAs. Both the 1.6 and 4.2 kb transcripts could be translated in vitro and were identified in vivo as being distributed on large polyribosomes. This indicates that both mRNAs are efficiently translated. Stability studies showed that in activated T-cells the 4.2 kb mRNA was more stable than the 1.6 kb mRNA. Polyadenylation site selection and mRNA stability differ for the two mRNAs of eIF-2 alpha. These activities might be modulated by sequence elements contained within the untranslated regions of the eIF-2 alpha gene.

The Drosophila melanogaster tumor suppressor gene lethal(3)malignant brain tumor encodes a proline-rich protein with a novel zinc finger

The lethal(3)malignant brain tumor [t(3)mbt] gene causes, when mutated, malignant growth of the adult optic neuroblasts and ganglion mother cells in the larval brain and imaginal disc overgrowth. Via overlapping deficiencies a genomic region of approximately 6.0 kb was identified, containing l(3)mbt+ gene sequences. The l(3)mbt+ gene encodes seven transcripts of 5.8 kb, 5.65 kb, 5.35 kb, 5.25 kb, 5.0 kb, 4.4 kb and 1.8 kb. The putative MBT163 protein, encompassing 1477 amino acids, is proline-rich and contains a novel zinc finger. In situ hybridizations of whole mount embryos and larval tissues revealed l(3)mbt+ RNA ubiquitously present in stage 1 embryos and throughout embryonic development in most tissues. In third instar larvae l(3)mbt+ RNA is detected in the adult optic anlagen and the imaginal discs, the tissues directly affected by l(3)mbt mutations, but also in tissues, showing normal development in the mutant, such as the gut, the goblet cells and the hematopoietic organs.

Cloning of cDNAs encoding the 160 kDa subunit of the bovine cleavage and polyadenylation specificity factor

3'-processing of mRNA precursors depends on several protein factors. One of them, cleavage and polyadenylation specificity factor (CPSF) is required for the cleavage of the mRNA precursor or as well as for the tail elongation reaction. We have obtained complementary DNA encoding the 160 kDa subunit, which had previously been shown to interact with the AAUAAA polyadenylation signal. The cDNAs code for an open reading frame of 1444 amino acids. The translated protein has a calculated molecular weight of 161 kDa and a predicted pl of 6.2. Polyclonal antibodies raised against a bacterially expressed fragment of the cDNA recognise 160 kDa subunit of purified calf thymus CPSF. The sequence contains a possible nuclear localisation signal but none of the known RNA binding motifs. It does, however, show sequence similarities to a UV-damaged DNA binding protein (UVdDb).

Cloning and characterization of a Xenopus poly(A) polymerase

During oocyte maturation and early embryogenesis in Xenopus laevis, the translation of several mRNAs is regulated by cytoplasmic poly(A) elongation, a reaction catalyzed by poly(A) polymerase (PAP). We have cloned, sequenced, and examined several biochemical properties of a Xenopus PAP. This protein is 87% identical to the amino-terminal portion of bovine PAP, which catalyzes the nuclear polyadenylation reaction, but lacks a large region of the corresponding carboxy terminus, which contains the nuclear localization signal. When injected into oocytes, the Xenopus PAP remains concentrated in the cytoplasm, suggesting that it is a specifically cytoplasmic enzyme. Oocytes contain several PAP mRNA-related transcripts, and the levels of at least the one encoding the putative cytoplasmic enzyme are relatively constant in oocytes and early embryos but decline after blastulation. When expressed in bacteria and purified by affinity and MonoQ-Sepharose chromatography, the protein has enzymatic activity and adds poly(A) to a model substrate. Importantly, affinity-purified antibodies directed against Xenopus PAP inhibit cytoplasmic polyadenylation in egg extracts. These data suggest that the PAP described here could participate in cytoplasmic polyadenylation during Xenopus oocyte maturation.

Two isoforms of Xenopus retinoic acid receptor gamma 2 (B) exhibit differential expression and sensitivity to retinoic acid during embryogenesis

We report the isolation of two retinoic acid receptor isoforms (RAR gamma), which differ only in the 5'untranslated and putative N-terminus A regions. The two isoforms appear to serve as early markers for the presumptive neural axis; however, their expression patterns differ. RAR-gamma 2.1 is first expressed at gastrulation at the dorsal lip and subsequently along the presumptive neural axis. RAR- gamma 2.2 represents the full-length sequence of a receptor cDNA already partially characterized and present as a maternal transcript [Ellinger-Ziegelbauer and Dreyer (1991); Genes Dev 5:94-104, (1993): Mech Dev 41:31-46; Pfeffer and DeRobertis, (1994) Mech Dev: 45:147-153]. Unlike RAR-gamma 2.2, the 2.1 variant is not expressed either in pre-somitic mesoderm or notochord. RAR-gamma 2.1 is strongly expressed in branchial arches and to a lesser extent in the neural floor plate. The two isoforms also exhibit differential sensitivity to retinoic acid. Constitutive expression of RAR gamma 2.2 following neurulation appears to be depressed by treatment with retinoic acid, but domains of highest expression, namely, the head and tail, remain relatively unaffected, as do patterns of expression prior to late neurulation. By contrast, RAR-gamma 2.1 is not transcribed in retinoid-inhibited structures. Using microinjection techniques, we show that changes of RAR-gamma 2.1 expression in presumptive head structures occur as an early and local consequence of retinoic acid administration. Since RAR-gamma 2.1 expression is inhibited by retinoic acid, we tested to see if other treatments that perturb axis formation had any effect. Surprisingly, UV irradiation did not suppress that its inhibition by retinoic acid is not due solely to inhibition of anterior neural development. These experiments demonstrate a new subdivision of isoforms that undergo differential expression during development and that exhibit differential sensitivity to retinoic acid and to UV. This sensitivity and the presence of this isoform variant in regions that are known to exhibit polarizing activity strengthen the hypothesis that these receptors play a primary role during morphogenesis.

Characterization of a Cu/Zn superoxide dismutase-encoding gene region in Drosophila willistoni

A Cu/Zn superoxide dismutase-encoding gene (Sod) from Drosophila willistoni was cloned and sequenced. The gene shows a typical structure for a fruit-fly Sod gene, with a coding region of 462 bp in two exons separated by a 417-bp intron. Comparison of the Sod sequences from D. willistoni and D. melanogaster suggests that these species are only remotely related. Downstream from the Sod gene, there is an ORF on the opposite strand that putatively encodes the last exon of an unidentified gene. The polyadenylation signals of the two genes are separated by only 61 bp in D. willistoni, conforming to the common picture of compact dipteran genomes.

Cloning of PBDX, an MIC2-related gene that spans the pseudoautosomal boundary on chromosome Xp

The pseudoautosomal boundaries are the interface between pseudoautosomal and sex chromosome-specific DNA sequences. We have isolated a gene, PBDX, from the human pseudoautosomal boundary region of Xp. The three exons at the 5' end of PBDX are situated in the pseudoautosomal region immediately downstream of MIC2, whereas the other seven exons are in the X-specific region. Hence, PBDX is inherited in two modes: its 5' end is pseudoautosomally inherited and its 3' end is X-linked. The predicted amino acid sequence of the 540 bp coding region is 48% homologous to 12E7, the product of MIC2. By virtue of its position, PBDX becomes an excellent candidate for the XG blood group gene.

The deadenylation conferred by the 3' untranslated region of a developmentally controlled mRNA in Xenopus embryos is switched to polyadenylation by deletion of a short sequence element

The maternal Xenopus Eg mRNAs are adenylated and translated in the mature oocyte and then, after fertilization, are deadenylated and released from polysomes. Therefore, after fertilization, a change occurs in the cellular mechanisms that control mRNA adenylation. In the study reported here, we show that the 3' untranslated region of Eg2 mRNA contains a cis-acting element that is required for the deadenylation of chimeric RNAs after fertilization. This cis-acting element is contained within a single 17-nucleotide portion of the Eg2 mRNA. Disruption of this deadenylation element allows adenylation of the chimeric transcripts in the embryo. Therefore, this cis-acting element is part of the sequence information required for the developmental switch from adenylation to deadenylation of the maternal Eg2 mRNA in Xenopus embryos.

The deadenylation conferred by the 3' untranslated region of a developmentally controlled mRNA in Xenopus embryos is switched to polyadenylation by deletion of a short sequence element

The maternal Xenopus Eg mRNAs are adenylated and translated in the mature oocyte and then, after fertilization, are deadenylated and released from polysomes. Therefore, after fertilization, a change occurs in the cellular mechanisms that control mRNA adenylation. In the study reported here, we show that the 3' untranslated region of Eg2 mRNA contains a cis-acting element that is required for the deadenylation of chimeric RNAs after fertilization. This cis-acting element is contained within a single 17-nucleotide portion of the Eg2 mRNA. Disruption of this deadenylation element allows adenylation of the chimeric transcripts in the embryo. Therefore, this cis-acting element is part of the sequence information required for the developmental switch from adenylation to deadenylation of the maternal Eg2 mRNA in Xenopus embryos.

Upstream and downstream cis-acting elements for cleavage at the L4 polyadenylation site of adenovirus-2

A study of the cis-acting elements involved in the 3' end formation of the RNAs from the major late L4 family of adenovirus-2 was undertaken. Series of 5' or 3' end deletion mutants and mutants harboring either internal deletions or substitutions were prepared and assayed for in vitro cleavage. This first allowed the demonstration of a sequence, located at -6 to -29, relative to AAUAAA, whose deletion or substitution reduces cleavage efficiency at the L4 polyadenylation site two to three fold. This upstream efficiency element 5' AUCUUUGUUGUC/AUCUCUGUGCUG 3' is constituted of a partially repeated 12 nucleotide long, UCG rich sequence. The activities of the 2 sequence elements in cleavage are additive. We also searched for regulatory sequences downstream of the L4 polyadenylation site. We found that the deletion or substitution of a 30 nucleotide long UCG rich sequence, between nucleotides +7 and +35 relative to the cleavage site and harboring a UCCUGU repeat reduces cleavage efficiency at least ten fold. A GUUUUU sequence, starting at +35 had no influence. Thus, the usage of the L4 polyadenylation site requires down-stream sequences different from the canonical GU or U boxes and is regulated by upstream sequence elements.

Purification, characterization, and cDNA cloning of an AU-rich element RNA-binding protein, AUF1

The degradation of some proto-oncogene and lymphokine mRNAs is controlled in part by an AU-rich element (ARE) in the 3' untranslated region. It was shown previously (G. Brewer, Mol. Cell. Biol. 11:2460-2466, 1991) that two polypeptides (37 and 40 kDa) copurified with fractions of a 130,000 x g postribosomal supernatant (S130) from K562 cells that selectively accelerated degradation of c-myc mRNA in a cell-free decay system. These polypeptides bound specifically to the c-myc and granulocyte-macrophage colony-stimulating factor 3' UTRs, suggesting they are in part responsible for selective mRNA degradation. In the present work, we have purified the RNA-binding component of this mRNA degradation activity, which we refer to as AUF1. Using antisera specific for these polypeptides, we demonstrate that the 37- and 40-kDa polypeptides are immunologically cross-reactive and that both polypeptides are phosphorylated and can be found in a complex(s) with other polypeptides. Immunologically related polypeptides are found in both the nucleus and the cytoplasm. The antibodies were also used to clone a cDNA for the 37-kDa polypeptide. This cDNA contains an open reading frame predicted to produce a protein with several features, including two RNA recognition motifs and domains that potentially mediate protein-protein interactions. These results provide further support for a role of this protein in mediating ARE-directed mRNA degradation.

Purification, characterization, and cDNA cloning of an AU-rich element RNA-binding protein, AUF1

The degradation of some proto-oncogene and lymphokine mRNAs is controlled in part by an AU-rich element (ARE) in the 3' untranslated region. It was shown previously (G. Brewer, Mol. Cell. Biol. 11:2460-2466, 1991) that two polypeptides (37 and 40 kDa) copurified with fractions of a 130,000 x g postribosomal supernatant (S130) from K562 cells that selectively accelerated degradation of c-myc mRNA in a cell-free decay system. These polypeptides bound specifically to the c-myc and granulocyte-macrophage colony-stimulating factor 3' UTRs, suggesting they are in part responsible for selective mRNA degradation. In the present work, we have purified the RNA-binding component of this mRNA degradation activity, which we refer to as AUF1. Using antisera specific for these polypeptides, we demonstrate that the 37- and 40-kDa polypeptides are immunologically cross-reactive and that both polypeptides are phosphorylated and can be found in a complex(s) with other polypeptides. Immunologically related polypeptides are found in both the nucleus and the cytoplasm. The antibodies were also used to clone a cDNA for the 37-kDa polypeptide. This cDNA contains an open reading frame predicted to produce a protein with several features, including two RNA recognition motifs and domains that potentially mediate protein-protein interactions. These results provide further support for a role of this protein in mediating ARE-directed mRNA degradation.

Purification and cDNA cloning of a transcription factor which functionally cooperates within a cAMP regulatory unit in the porcine uPA gene

One of cAMP-regulatory sites in the porcine urokinase-type plasminogen activator (uPA) gene resides 3.4 kb upstream of the transcription initiation site and is composed of three protein binding domains, FPA, FPB and FPC. Whereas FPA and FPB contain a CRE-like sequence, the FPC sequence is not related to any known protein recognition sequences, yet all three domains are required to mediate cAMP action on a heterologous promoter. To study the functional cooperation among these three domains we purified and cloned a FPC-binding protein (FPCB) from porcine kidney derived LLC-PK1 cells. Sequence comparisons showed that FPCB is homologous to mouse LFB3 and rat vHNF1. LFB3/vHNF1 is related to a liver specific transcription factor HNF1, it recognizes the same sequence as HNF1 and is highly expressed in kidney cells. FPCB and HNF1 recognition sequences are dissimilar, nevertheless both sequences are recognized by in vitro-translated LFB3 and FPCB, indicating that binding to the two different sequences is an intrinsic character of FPCB/LFB3/vHNF1. In HeLa cells, this cAMP-responsive site was inactive whether FPCB was overexpressed or not, suggesting a requirement for an additional cell-specific factor. These results may suggest a mechanism by which hormonal control is integrated into cell-specific gene regulation.

Human gene mutations affecting RNA processing and translation

Gene mutations affecting mRNA processing and translation are not common causes of human genetic disease. Their analysis has nevertheless provided important insights into the basic biochemical mechanisms underlying mRNA transcription and translation.