A translation factor that gates the progression of the 70S ribosomal initiation complex (IC, containing tRNA(fMet) in the P-site) into the translation elongation cycle by using a mechanism sensitive to the ATP/ADP ratio. Binds to the 70S ribosome E-site where it modulates the state of the translating ribosome during subunit translocation. ATP hydrolysis probably frees it from the ribosome, which can enter the elongation phase.
Belongs to the ABC transporter superfamily. ABCF family. Translational throttle EttA subfamily.
Lacks conserved residue(s) required for the propagation of feature annotation.
Monomer. Probably contacts ribosomal proteins L1, L5, L33 and S7, the 16S and 23S rRNA and the P-site containing tRNA(fMet).
The P-site tRNA interaction motif (PtIM domain) probably interacts with the P-site tRNA(fMet) as well as the 23S rRNA.
The arm domain is inserted in the first ABC transporter domain. Probably contacts ribosomal protein L1.
Belongs to the GTP-binding SRP family. SRP54 subfamily.
Composed of three domains: the N-terminal N domain, which is responsible for interactions with the ribosome, the central G domain, which binds GTP, and the C-terminal M domain, which binds the RNA and the signal sequence of the RNC.
Involved in targeting and insertion of nascent membrane proteins into the cytoplasmic membrane. Binds to the hydrophobic signal sequence of the ribosome-nascent chain (RNC) as it emerges from the ribosomes. The SRP-RNC complex is then targeted to the cytoplasmic membrane where it interacts with the SRP receptor FtsY.
Part of the signal recognition particle protein translocation system, which is composed of SRP and FtsY.
Belongs to the phosphofructokinase type A (PFKA) family. Mixed-substrate PFK group III subfamily.
Catalyzes the phosphorylation of D-fructose 6-phosphate to fructose 1,6-bisphosphate by ATP, the first committing step of glycolysis.
Belongs to the bacterial ribosomal protein bL35 family.
Component of the F(0) channel, it forms part of the peripheral stalk, linking F(1) to F(0).
F(1)F(0) ATP synthase produces ATP from ADP in the presence of a proton or sodium gradient. F-type ATPases consist of two structural domains, F(1) containing the extramembraneous catalytic core and F(0) containing the membrane proton channel, linked together by a central stalk and a peripheral stalk. During catalysis, ATP synthesis in the catalytic domain of F(1) is coupled via a rotary mechanism of the central stalk subunits to proton translocation.
F-type ATPases have 2 components, F(1) - the catalytic core - and F(0) - the membrane proton channel. F(1) has five subunits: alpha(3), beta(3), gamma(1), delta(1), epsilon(1). F(0) has three main subunits: a(1), b(2) and c(10-14). The alpha and beta chains form an alternating ring which encloses part of the gamma chain. F(1) is attached to F(0) by a central stalk formed by the gamma and epsilon chains, while a peripheral stalk is formed by the delta and b chains.
Belongs to the ATPase epsilon chain family.
F-type ATPases have 2 components, CF(1) - the catalytic core - and CF(0) - the membrane proton channel. CF(1) has five subunits: alpha(3), beta(3), gamma(1), delta(1), epsilon(1). CF(0) has three main subunits: a, b and c.
Produces ATP from ADP in the presence of a proton gradient across the membrane.
A 50S ribosomal subunit assembly protein with GTPase activity, required for 50S subunit assembly at low temperatures, may also play a role in translation. Binds GTP and analogs. Binds the 70S ribosome between the 30S and 50S subunits, in a similar position as ribosome-bound EF-G; it contacts a number of ribosomal proteins, both rRNAs and the A-site tRNA.
Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. BipA subfamily.
Belongs to the radical SAM superfamily. Biotin synthase family.
Binds 1 [2Fe-2S] cluster. The cluster is coordinated with 3 cysteines and 1 arginine.
Binds 1 [4Fe-4S] cluster. The cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine.
Catalyzes the conversion of dethiobiotin (DTB) to biotin by the insertion of a sulfur atom into dethiobiotin via a radical-based mechanism.
Belongs to the iron/manganese superoxide dismutase family.
Destroys radicals which are normally produced within the cells and which are toxic to biological systems.
Destroys superoxide anion radicals which are normally produced within the cells and which are toxic to biological systems.
Belongs to the universal ribosomal protein uS10 family.
Involved in the binding of tRNA to the ribosomes.
Belongs to the uracil-DNA glycosylase (UDG) superfamily. UNG family.
Excises uracil residues from the DNA which can arise as a result of misincorporation of dUMP residues by DNA polymerase or due to deamination of cytosine.
Belongs to the universal ribosomal protein uS11 family.
Located on the platform of the 30S subunit, it bridges several disparate RNA helices of the 16S rRNA. Forms part of the Shine-Dalgarno cleft in the 70S ribosome.
Part of the 30S ribosomal subunit. Interacts with proteins S7 and S18. Binds to IF-3.
Belongs to the bacterial ribosomal protein bL36 family.
Belongs to the bacterial ribosomal protein bS16 family.
Belongs to the ABC transporter superfamily. Ycf16 family.
Belongs to the universal ribosomal protein uS4 family.
One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the body of the 30S subunit.
Part of the 30S ribosomal subunit. Contacts protein S5. The interaction surface between S4 and S5 is involved in control of translational fidelity.
With S5 and S12 plays an important role in translational accuracy.
Belongs to the ATPase alpha/beta chains family.
Produces ATP from ADP in the presence of a proton gradient across the membrane. The catalytic sites are hosted primarily by the beta subunits.
Belongs to the universal ribosomal protein uL29 family.
Catalyzes the reversible phosphorylation of UMP to UDP.
Belongs to the bacterial ribosomal protein bL28 family.
Participates in transcription elongation, termination and antitermination.
Allows the formation of correctly charged Asn-tRNA(Asn) or Gln-tRNA(Gln) through the transamidation of misacylated Asp-tRNA(Asn) or Glu-tRNA(Gln) in organisms which lack either or both of asparaginyl-tRNA or glutaminyl-tRNA synthetases. The reaction takes place in the presence of glutamine and ATP through an activated phospho-Asp-tRNA(Asn) or phospho-Glu-tRNA(Gln).
Belongs to the universal ribosomal protein uS7 family.
One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the head domain of the 30S subunit. Is located at the subunit interface close to the decoding center, probably blocks exit of the E-site tRNA.
Part of the 30S ribosomal subunit. Contacts proteins S9 and S11.
Belongs to the RNA polymerase subunit omega family.
Promotes RNA polymerase assembly. Latches the N- and C-terminal regions of the beta' subunit thereby facilitating its interaction with the beta and alpha subunits.
The RNAP catalytic core consists of 2 alpha, 1 beta, 1 beta' and 1 omega subunit. When a sigma factor is associated with the core the holoenzyme is formed, which can initiate transcription.
Belongs to the universal ribosomal protein uS15 family.
Forms an intersubunit bridge (bridge B4) with the 23S rRNA of the 50S subunit in the ribosome.
One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it helps nucleate assembly of the platform of the 30S subunit by binding and bridging several RNA helices of the 16S rRNA.
Part of the 30S ribosomal subunit. Forms a bridge to the 50S subunit in the 70S ribosome, contacting the 23S rRNA.
Belongs to the class-I pyridine nucleotide-disulfide oxidoreductase family.
The active site is a redox-active disulfide bond.
Belongs to the bacterial ribosomal protein bL34 family.
Acts as a transcriptional regulator. Probably redox-responsive. The apo- but not holo-form probably binds DNA.
Binds 1 [4Fe-4S] cluster per subunit. Following nitrosylation of the [4Fe-4S] cluster binds 1 [4Fe-8(NO)] cluster per subunit.
The Fe-S cluster can be nitrosylated by nitric oxide (NO).
Upon Fe-S cluster removal intramolecular disulfide bonds are formed.
Participates actively in the response to hyperosmotic and heat shock by preventing the aggregation of stress-denatured proteins and by disaggregating proteins, also in an autonomous, DnaK-independent fashion. Unfolded proteins bind initially to DnaJ; upon interaction with the DnaJ-bound protein, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable complex. GrpE releases ADP from DnaK; ATP binding to DnaK triggers the release of the substrate protein, thus completing the reaction cycle. Several rounds of ATP-dependent interactions between DnaJ, DnaK and GrpE are required for fully efficient folding. Also involved, together with DnaK and GrpE, in the DNA replication of plasmids through activation of initiation proteins.
The J domain is necessary and sufficient to stimulate DnaK ATPase activity. Zinc center 1 plays an important role in the autonomous, DnaK-independent chaperone activity of DnaJ. Zinc center 2 is essential for interaction with DnaK and for DnaJ activity.
Belongs to the elongation factor P family.
Involved in peptide bond synthesis. Stimulates efficient translation and peptide-bond synthesis on native or reconstituted 70S ribosomes in vitro. Probably functions indirectly by altering the affinity of the ribosome for aminoacyl-tRNA, thus increasing their reactivity as acceptors for peptidyl transferase.
Belongs to the universal ribosomal protein uL23 family.
One of the early assembly proteins it binds 23S rRNA. One of the proteins that surrounds the polypeptide exit tunnel on the outside of the ribosome. Forms the main docking site for trigger factor binding to the ribosome.
Part of the 50S ribosomal subunit. Contacts protein L29, and trigger factor when it is bound to the ribosome.
Belongs to the universal ribosomal protein uL15 family.
Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. LepA subfamily.
Required for accurate and efficient protein synthesis under certain stress conditions. May act as a fidelity factor of the translation reaction, by catalyzing a one-codon backward translocation of tRNAs on improperly translocated ribosomes. Back-translocation proceeds from a post-translocation (POST) complex to a pre-translocation (PRE) complex, thus giving elongation factor G a second chance to translocate the tRNAs correctly. Binds to ribosomes in a GTP-dependent manner.
Negatively regulates transcription of bacterial ribonucleotide reductase nrd genes and operons by binding to NrdR-boxes.
Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. EF-Tu/EF-1A subfamily.
This protein promotes the GTP-dependent binding of aminoacyl-tRNA to the A-site of ribosomes during protein biosynthesis.
Responsible for the release of ribosomes from messenger RNA at the termination of protein biosynthesis. May increase the efficiency of translation by recycling ribosomes from one round of translation to another.
Belongs to the ABC transporter superfamily.
ATPase that binds to both the 70S ribosome and the 50S ribosomal subunit in a nucleotide-independent manner.
Belongs to the TRAFAC class OBG-HflX-like GTPase superfamily. OBG GTPase family. YchF/OLA1 subfamily.
Belongs to the binding-protein-dependent transport system permease family.
Associates with subunits I, II and III to form cytochrome c oxidase.
Belongs to the cytochrome c oxidase bacterial subunit CtaF family.
Part of cytochrome c oxidase, its function is unknown.
May play a role in DNA repair. It seems to be involved in an RecBC-independent recombinational process of DNA repair. It may act with RecF and RecO.
Functions as a ribosomal silencing factor. Interacts with ribosomal protein L14 (rplN), blocking formation of intersubunit bridge B8. Prevents association of the 30S and 50S ribosomal subunits and the formation of functional ribosomes, thus repressing translation.
Interacts with ribosomal protein L14 (rplN).
Belongs to the universal ribosomal protein uL16 family.
Binds 23S rRNA and is also seen to make contacts with the A and possibly P site tRNAs.
Belongs to the bacterial ribosomal protein bL27 family.
Belongs to the universal stress protein A family.
Belongs to the heme-copper respiratory oxidase family.
Cytochrome c oxidase is the component of the respiratory chain that catalyzes the reduction of oxygen to water. Subunits 1-3 form the functional core of the enzyme complex. CO I is the catalytic subunit of the enzyme. Electrons originating in cytochrome c are transferred via the copper A center of subunit 2 and heme A of subunit 1 to the bimetallic center formed by heme A3 and copper B.
Belongs to the universal ribosomal protein uL22 family.
The globular domain of the protein is located near the polypeptide exit tunnel on the outside of the subunit, while an extended beta-hairpin is found that lines the wall of the exit tunnel in the center of the 70S ribosome.
This protein binds specifically to 23S rRNA; its binding is stimulated by other ribosomal proteins, e.g. L4, L17, and L20. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome.
This protein binds specifically to 23S rRNA; its binding is stimulated by other ribosomal proteins, e.g., L4, L17, and L20. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome.
Key component of the F(0) channel; it plays a direct role in translocation across the membrane. A homomeric c-ring of between 10-14 subunits forms the central stalk rotor element with the F(1) delta and epsilon subunits.
Belongs to the bacterial ribosomal protein bL9 family.
Belongs to the bacterial ribosomal protein bL32 family.
Required for rescue of stalled ribosomes mediated by trans-translation. Binds to transfer-messenger RNA (tmRNA), required for stable association of tmRNA with ribosomes. tmRNA and SmpB together mimic tRNA shape, replacing the anticodon stem-loop with SmpB. tmRNA is encoded by the ssrA gene; the 2 termini fold to resemble tRNA(Ala) and it encodes a 'tag peptide', a short internal open reading frame. During trans-translation Ala-aminoacylated tmRNA acts like a tRNA, entering the A-site of stalled ribosomes, displacing the stalled mRNA. The ribosome then switches to translate the ORF on the tmRNA; the nascent peptide is terminated with the 'tag peptide' encoded by the tmRNA and targeted for degradation. The ribosome is freed to recommence translation, which seems to be the essential function of trans-translation.
Belongs to the bacterial ribosomal protein bS18 family.
Binds as a heterodimer with protein S6 to the central domain of the 16S rRNA, where it helps stabilize the platform of the 30S subunit.
Part of the 30S ribosomal subunit. Forms a tight heterodimer with protein S6.
Belongs to the universal ribosomal protein uL4 family.
Forms part of the polypeptide exit tunnel.
One of the primary rRNA binding proteins, this protein initially binds near the 5'-end of the 23S rRNA. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome.
Belongs to the universal ribosomal protein uL11 family.
Forms part of the ribosomal stalk which helps the ribosome interact with GTP-bound translation factors.
One or more lysine residues are methylated.
Part of the ribosomal stalk of the 50S ribosomal subunit. Interacts with L10 and the large rRNA to form the base of the stalk. L10 forms an elongated spine to which L12 dimers bind in a sequential fashion forming a multimeric L10(L12)X complex.
Involved in protein export. Participates in an early event of protein translocation.
Belongs to the acetolactate synthase small subunit family.
Catalyzes the conversion of 2 pyruvate molecules into acetolactate in the first common step of the biosynthetic pathway of the branched-amino acids such as leucine, isoleucine, and valine.
Belongs to the bacterial ribosomal protein bL33 family.
Bifunctional enzyme that catalyzes both the deamination of dCTP to dUTP and the hydrolysis of dUTP to dUMP without releasing the toxic dUTP intermediate.
Belongs to the bacterial ribosomal protein bL31 family. Type B subfamily.
Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released.
Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins.
Fourteen ClpP subunits assemble into 2 heptameric rings which stack back to back to give a disk-like structure with a central cavity, resembling the structure of eukaryotic proteasomes.
Belongs to the universal ribosomal protein uS12 family.
Interacts with and stabilizes bases of the 16S rRNA that are involved in tRNA selection in the A site and with the mRNA backbone. Located at the interface of the 30S and 50S subunits, it traverses the body of the 30S subunit contacting proteins on the other side and probably holding the rRNA structure together. The combined cluster of proteins S8, S12 and S17 appears to hold together the shoulder and platform of the 30S subunit.
Part of the 30S ribosomal subunit. Contacts proteins S8 and S17. May interact with IF1 in the 30S initiation complex.
With S4 and S5 plays an important role in translational accuracy.
Belongs to the universal ribosomal protein uL5 family.
Part of the 50S ribosomal subunit; part of the 5S rRNA/L5/L18/L25 subcomplex. Contacts the 5S rRNA and the P site tRNA. Forms a bridge to the 30S subunit in the 70S ribosome.
This is 1 of the proteins that binds and probably mediates the attachment of the 5S RNA into the large ribosomal subunit, where it forms part of the central protuberance. In the 70S ribosome it contacts protein S13 of the 30S subunit (bridge B1b), connecting the 2 subunits; this bridge is implicated in subunit movement. Contacts the P site tRNA; the 5S rRNA and some of its associated proteins might help stabilize positioning of ribosome-bound tRNAs.
Belongs to the universal ribosomal protein uL10 family.
Forms part of the ribosomal stalk, playing a central role in the interaction of the ribosome with GTP-bound translation factors.
Part of the ribosomal stalk of the 50S ribosomal subunit. The N-terminus interacts with L11 and the large rRNA to form the base of the stalk. The C-terminus forms an elongated spine to which L12 dimers bind in a sequential fashion forming a multimeric L10(L12)X complex.
Belongs to the bacterial ribosomal protein bL20 family.
Binds directly to 23S ribosomal RNA and is necessary for the in vitro assembly process of the 50S ribosomal subunit. It is not involved in the protein synthesizing functions of that subunit.
Belongs to the universal ribosomal protein uS3 family.
Binds the lower part of the 30S subunit head. Binds mRNA in the 70S ribosome, positioning it for translation.
Part of the 30S ribosomal subunit. Forms a tight complex with proteins S10 and S14.
Belongs to the RNA polymerase-binding protein RbpA family.
Binds to RNA polymerase (RNAP), stimulating transcription from principal, but not alternative sigma factor promoters.
Forms a complex with the RNAP catalytic core and with free principal sigma factors.
Belongs to the bacterial ribosomal protein bL17 family.
Part of the 50S ribosomal subunit. Contacts protein L32.
Monomer. Binds 30S ribosomal subunits, but not 50S ribosomal subunits or 70S ribosomes.
One of several proteins that assist in the late maturation steps of the functional core of the 30S ribosomal subunit. Associates with free 30S ribosomal subunits (but not with 30S subunits that are part of 70S ribosomes or polysomes). Required for efficient processing of 16S rRNA. May interact with the 5'-terminal helix region of 16S rRNA.
Ferredoxins are iron-sulfur proteins that transfer electrons in a wide variety of metabolic reactions.
Part of the twin-arginine translocation (Tat) system that transports large folded proteins containing a characteristic twin-arginine motif in their signal peptide across membranes. TatA could form the protein-conducting channel of the Tat system.
The Tat system comprises two distinct complexes: a TatABC complex, containing multiple copies of TatA, TatB and TatC subunits, and a separate TatA complex, containing only TatA subunits. Substrates initially bind to the TatABC complex, which probably triggers association of the separate TatA complex to form the active translocon.
Belongs to the bacterial ribosomal protein bS6 family.
Binds together with S18 to 16S ribosomal RNA.
Belongs to the bacterial ribosomal protein bL21 family.
Part of the 50S ribosomal subunit. Contacts protein L20.
This protein binds to 23S rRNA in the presence of protein L20.
Catalyzes the formation of pyridoxal 5'-phosphate from ribose 5-phosphate (RBP), glyceraldehyde 3-phosphate (G3P) and ammonia. The ammonia is provided by the PdxT subunit. Can also use ribulose 5-phosphate and dihydroxyacetone phosphate as substrates, resulting from enzyme-catalyzed isomerization of RBP and G3P, respectively.
In the presence of PdxT, forms a dodecamer of heterodimers.
Belongs to the PNP/UDP phosphorylase family.
Belongs to the universal ribosomal protein uS5 family.
Located at the back of the 30S subunit body where it stabilizes the conformation of the head with respect to the body.
Part of the 30S ribosomal subunit. Contacts proteins S4 and S8.
The N-terminal domain interacts with the head of the 30S subunit; the C-terminal domain interacts with the body and contacts protein S4. The interaction surface between S4 and S5 is involved in control of translational fidelity.
With S4 and S12 plays an important role in translational accuracy.
Heptamer of 7 subunits arranged in a ring. Interacts with the chaperonin GroEL.
Together with the chaperonin GroEL, plays an essential role in assisting protein folding. The GroEL-GroES system forms a nano-cage that allows encapsulation of the non-native substrate proteins and provides a physical environment optimized to promote and accelerate protein folding. GroES binds to the apical surface of the GroEL ring, thereby capping the opening of the GroEL channel.
Component of the 30S ribosomal translation pre-initiation complex which assembles on the 30S ribosome in the order IF-2 and IF-3, IF-1 and N-formylmethionyl-tRNA(fMet); mRNA recruitment can occur at any time during PIC assembly.
One of the essential components for the initiation of protein synthesis. Stabilizes the binding of IF-2 and IF-3 on the 30S subunit to which N-formylmethionyl-tRNA(fMet) subsequently binds. Helps modulate mRNA selection, yielding the 30S pre-initiation complex (PIC). Upon addition of the 50S ribosomal subunit IF-1, IF-2 and IF-3 are released leaving the mature 70S translation initiation complex.
Belongs to the universal ribosomal protein uL13 family.
This protein is one of the early assembly proteins of the 50S ribosomal subunit, although it is not seen to bind rRNA by itself. It is important during the early stages of 50S assembly.
Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. EF-G/EF-2 subfamily.
Catalyzes the GTP-dependent ribosomal translocation step during translation elongation. During this step, the ribosome changes from the pre-translocational (PRE) to the post-translocational (POST) state as the newly formed A-site-bound peptidyl-tRNA and P-site-bound deacylated tRNA move to the P and E sites, respectively. Catalyzes the coordinated movement of the two tRNA molecules, the mRNA and conformational changes in the ribosome.
Belongs to the purine/pyrimidine phosphoribosyltransferase family. PyrE subfamily.
Catalyzes the transfer of a ribosyl phosphate group from 5-phosphoribose 1-diphosphate to orotate, leading to the formation of orotidine monophosphate (OMP).
Belongs to the ammonia transporter channel (TC 1.A.11.2) family.
Belongs to the universal ribosomal protein uS8 family.
One of the primary rRNA binding proteins, it binds directly to 16S rRNA central domain where it helps coordinate assembly of the platform of the 30S subunit.
Part of the 30S ribosomal subunit. Contacts proteins S5 and S12.
Belongs to the universal ribosomal protein uS19 family.
Protein S19 forms a complex with S13 that binds strongly to the 16S ribosomal RNA.
Belongs to the ABC-3 integral membrane protein family.
Homodimer. Forms a membrane-associated complex with FtsX.
Part of the ABC transporter FtsEX involved in cellular division.
Belongs to the universal ribosomal protein uL3 family.
One of the primary rRNA binding proteins, it binds directly near the 3'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit.
Part of the 50S ribosomal subunit. Forms a cluster with proteins L14 and L19.
Electron transport system for the ribonucleotide reductase system NrdEF.
Belongs to the universal ribosomal protein uL14 family.
Binds to 23S rRNA. Forms part of two intersubunit bridges in the 70S ribosome.
Part of the 50S ribosomal subunit. Forms a cluster with proteins L3 and L19. In the 70S ribosome, L14 and L19 interact and together make contacts with the 16S rRNA in bridges B5 and B8.
Belongs to the bacterial ribosomal protein bL12 family.
Forms part of the ribosomal stalk which helps the ribosome interact with GTP-bound translation factors. Is thus essential for accurate translation.
Homodimer. Part of the ribosomal stalk of the 50S ribosomal subunit. Forms a multimeric L10(L12)X complex, where L10 forms an elongated spine to which 2 to 4 L12 dimers bind in a sequential fashion. Binds GTP-bound translation factors.
Belongs to the GTP-binding SRP family. FtsY subfamily.
Involved in targeting and insertion of nascent membrane proteins into the cytoplasmic membrane. Acts as a receptor for the complex formed by the signal recognition particle (SRP) and the ribosome-nascent chain (RNC).