Channel that opens in response to stretch forces in the membrane lipid bilayer. May participate in the regulation of osmotic pressure changes within the cell.
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).
Part of the signal recognition particle protein translocation system, which is composed of SRP and FtsY.
Belongs to the sigma-70 factor family. ECF subfamily.
Belongs to the adenylate cyclase family. DacA/CdaA subfamily.
Catalyzes the condensation of 2 ATP molecules into cyclic di-AMP (c-di-AMP), a second messenger used to regulate differing processes in different bacteria.
Lacks conserved residue(s) required for the propagation of feature annotation.
Belongs to the purine/pyrimidine phosphoribosyltransferase family.
Catalyzes a salvage reaction resulting in the formation of AMP, that is energically less costly than de novo synthesis.
Belongs to the ribonucleoside diphosphate reductase small chain family.
Provides the precursors necessary for DNA synthesis. Catalyzes the biosynthesis of deoxyribonucleotides from the corresponding ribonucleotides.
Tetramer of two alpha and two beta subunits.
Belongs to the complex I subunit 3 family.
NDH-1 is composed of 14 different subunits. Subunits NuoA, H, J, K, L, M, N constitute the membrane sector of the complex.
NDH-1 shuttles electrons from NADH, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is believed to be a menaquinone. Couples the redox reaction to proton translocation (for every two electrons transferred, four hydrogen ions are translocated across the cytoplasmic membrane), and thus conserves the redox energy in a proton gradient.
The glycine cleavage system catalyzes the degradation of glycine. The H protein shuttles the methylamine group of glycine from the P protein to the T protein.
The glycine cleavage system is composed of four proteins: P, T, L and H.
Belongs to the ferritin family. Prokaryotic subfamily.
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.
Binds 1 pyruvoyl group covalently per subunit.
Catalyzes the pyruvoyl-dependent decarboxylation of aspartate to produce beta-alanine.
Heterooctamer of four alpha and four beta subunits.
Is synthesized initially as an inactive proenzyme, which is activated by self-cleavage at a specific serine bond to produce a beta-subunit with a hydroxyl group at its C-terminus and an alpha-subunit with a pyruvoyl group at its N-terminus.
Belongs to the radical SAM superfamily. RlmN family.
Binds 1 [4Fe-4S] cluster. The cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine.
Reaction proceeds by a ping-pong mechanism involving intermediate methylation of a conserved cysteine residue.
Specifically methylates position 2 of adenine 2503 in 23S rRNA and position 2 of adenine 37 in tRNAs.
Belongs to the succinate/malate CoA ligase alpha subunit family.
Heterotetramer of two alpha and two beta subunits.
Succinyl-CoA synthetase functions in the citric acid cycle (TCA), coupling the hydrolysis of succinyl-CoA to the synthesis of either ATP or GTP and thus represents the only step of substrate-level phosphorylation in the TCA. The alpha subunit of the enzyme binds the substrates coenzyme A and phosphate, while succinate binding and nucleotide specificity is provided by the beta subunit.
Belongs to the bacterial ribosomal protein bL31 family. Type B subfamily.
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.
Cell division protein that is involved in the assembly of the Z ring. May serve as a membrane anchor for the Z ring.
Belongs to the universal ribosomal protein uL30 family.
Belongs to the class-I aminoacyl-tRNA synthetase family.
Belongs to the universal stress protein A family.
Belongs to the glutamine synthetase family.
Belongs to the aconitase/IPM isomerase family. LeuC type 1 subfamily.
Catalyzes the isomerization between 2-isopropylmalate and 3-isopropylmalate, via the formation of 2-isopropylmaleate.
Nuclease that resolves Holliday junction intermediates in genetic recombination. Cleaves the cruciform structure in supercoiled DNA by nicking to strands with the same polarity at sites symmetrically opposed at the junction in the homologous arms and leaves a 5'-terminal phosphate and a 3'-terminal hydroxyl group.
Belongs to the methylglyoxal synthase family.
Catalyzes the formation of methylglyoxal from dihydroxyacetone phosphate.
Might have a role analogous to that of eukaryotic histone proteins.
Belongs to the universal ribosomal protein uL1 family.
Binds directly to 23S rRNA. The L1 stalk is quite mobile in the ribosome, and is involved in E site tRNA release.
Protein L1 is also a translational repressor protein, it controls the translation of the L11 operon by binding to its mRNA.
Belongs to the transaldolase family. Type 3B subfamily.
Transaldolase is important for the balance of metabolites in the pentose-phosphate pathway.
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.
Belongs to the radical SAM superfamily. 7-carboxy-7-deazaguanine synthase family.
Binds 1 S-adenosyl-L-methionine per subunit.
Catalyzes the complex heterocyclic radical-mediated conversion of 6-carboxy-5,6,7,8-tetrahydropterin (CPH4) to 7-carboxy-7-deazaguanine (CDG), a step common to the biosynthetic pathways of all 7-deazapurine-containing compounds.
Belongs to the RNA polymerase beta chain family.
DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.
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 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 class-II pyridoxal-phosphate-dependent aminotransferase family.
Catalyzes the condensation of L-serine with palmitoyl-CoA (hexadecanoyl-CoA) to produce 3-oxosphinganine.
Binds to DNA and alters its conformation. May be involved in regulation of gene expression, nucleoid organization and DNA protection.
Component of the Sec protein translocase complex. Heterotrimer consisting of SecY, SecE and SecG subunits. The heterotrimers can form oligomers, although 1 heterotrimer is thought to be able to translocate proteins. Interacts with the ribosome. Interacts with SecDF, and other proteins may be involved. Interacts with SecA.
Essential subunit of the Sec protein translocation channel SecYEG. Clamps together the 2 halves of SecY. May contact the channel plug during translocation.
An accessory protein needed during the final step in the assembly of 30S ribosomal subunit, possibly for assembly of the head region. Probably interacts with S19. Essential for efficient processing of 16S rRNA. May be needed both before and after RbfA during the maturation of 16S rRNA. It has affinity for free ribosomal 30S subunits but not for 70S ribosomes.
The PRC barrel domain binds ribosomal protein S19.
Belongs to the ABC-4 integral membrane protein family. FtsX subfamily.
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.
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.
Belongs to the acyl coenzyme A hydrolase family.
Can catalyze the hydrolysis of ATP in the presence of single-stranded DNA, the ATP-dependent uptake of single-stranded DNA by duplex DNA, and the ATP-dependent hybridization of homologous single-stranded DNAs. It interacts with LexA causing its activation and leading to its autocatalytic cleavage.
Belongs to the universal ribosomal protein uS14 family.
Binds 16S rRNA, required for the assembly of 30S particles and may also be responsible for determining the conformation of the 16S rRNA at the A site.
Part of the 30S ribosomal subunit. Contacts proteins S3 and S10.
Belongs to the peroxiredoxin family. Tpx subfamily.
The active site is a conserved redox-active cysteine residue, the peroxidatic cysteine (C(P)), which makes the nucleophilic attack on the peroxide substrate. The peroxide oxidizes the C(P)-SH to cysteine sulfenic acid (C(P)-SOH), which then reacts with another cysteine residue, the resolving cysteine (C(R)), to form a disulfide bridge. The disulfide is subsequently reduced by an appropriate electron donor to complete the catalytic cycle. In this atypical 2-Cys peroxiredoxin, C(R) is present in the same subunit to form an intramolecular disulfide. The disulfide is subsequently reduced by thioredoxin.
Thiol-specific peroxidase that catalyzes the reduction of hydrogen peroxide and organic hydroperoxides to water and alcohols, respectively. Plays a role in cell protection against oxidative stress by detoxifying peroxides.
Belongs to the glycosyltransferase 51 family.
Peptidoglycan polymerase that catalyzes glycan chain elongation from lipid-linked precursors.
Belongs to the bacterial ribosomal protein bL19 family.
This protein is located at the 30S-50S ribosomal subunit interface and may play a role in the structure and function of the aminoacyl-tRNA binding site.
Acetyl-CoA carboxylase is a heterohexamer composed of biotin carboxyl carrier protein (AccB), biotin carboxylase (AccC) and two subunits each of ACCase subunit alpha (AccA) and ACCase subunit beta (AccD).
Component of the acetyl coenzyme A carboxylase (ACC) complex. Biotin carboxylase (BC) catalyzes the carboxylation of biotin on its carrier protein (BCCP) and then the CO(2) group is transferred by the transcarboxylase to acetyl-CoA to form malonyl-CoA.
Catalyzes the complicated ring closure reaction between the two acyclic compounds 1-deoxy-D-xylulose-5-phosphate (DXP) and 3-amino-2-oxopropyl phosphate (1-amino-acetone-3-phosphate or AAP) to form pyridoxine 5'-phosphate (PNP) and inorganic phosphate.
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.
Binds 1 pyridoxal phosphate per subunit.
Catalyzes the cleavage of 2-amino-3-ketobutyrate to glycine and acetyl-CoA.
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 fatty acid desaturase type 2 family.
Plays an important role in the initiation and regulation of chromosomal replication. Binds to the origin of replication; it binds specifically double-stranded DNA at a 9 bp consensus (dnaA box): 5'-TTATC[CA]A[CA]A-3'. DnaA binds to ATP and to acidic phospholipids.
Belongs to the complex I subunit 4L family.
Belongs to the bacterial ribosomal protein bL35 family.
Belongs to the universal ribosomal protein uL29 family.
Belongs to the cyclophilin-type PPIase family.
PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides.
Belongs to the PTPS family. QueD subfamily.
Belongs to the binding-protein-dependent transport system permease family.
Catalyzes the hydrolysis of inorganic pyrophosphate (PPi) forming two phosphate ions.
Belongs to the drug/metabolite transporter (DMT) superfamily. Small multidrug resistance (SMR) (TC 2.A.7.1) family.
Belongs to the zinc-containing alcohol dehydrogenase family.
Belongs to the thiolase-like superfamily. FabH family.
Catalyzes the condensation reaction of fatty acid synthesis by the addition to an acyl acceptor of two carbons from malonyl-ACP. Catalyzes the first condensation reaction which initiates fatty acid synthesis and may therefore play a role in governing the total rate of fatty acid production. Possesses both acetoacetyl-ACP synthase and acetyl transacylase activities. Its substrate specificity determines the biosynthesis of branched-chain and/or straight-chain of fatty acids.
The last Arg residue of the ACP-binding site is essential for the weak association between ACP/AcpP and FabH.
Belongs to the deoxyhypusine synthase family.
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 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.
Belongs to the SurE nucleotidase family.
Binds 1 divalent metal cation per subunit.
Nucleotidase that shows phosphatase activity on nucleoside 5'-monophosphates.
Belongs to the bacterial ribosomal protein bL33 family.
The central subunit of the protein translocation channel SecYEG. Consists of two halves formed by TMs 1-5 and 6-10. These two domains form a lateral gate at the front which open onto the bilayer between TMs 2 and 7, and are clamped together by SecE at the back. The channel is closed by both a pore ring composed of hydrophobic SecY resides and a short helix (helix 2A) on the extracellular side of the membrane which forms a plug. The plug probably moves laterally to allow the channel to open. The ring and the pore may move independently.
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 uL2 family.
One of the primary rRNA binding proteins. Required for association of the 30S and 50S subunits to form the 70S ribosome, for tRNA binding and peptide bond formation. It has been suggested to have peptidyltransferase activity; this is somewhat controversial. Makes several contacts with the 16S rRNA in the 70S ribosome.
Part of the 50S ribosomal subunit. Forms a bridge to the 30S subunit in the 70S ribosome.
Belongs to the bacterial ribosomal protein bS20 family.
Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily.
Belongs to the peroxiredoxin family. Prx6 subfamily.
Belongs to the complex I 23 kDa subunit family.
NDH-1 shuttles electrons from NADH, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is believed to be ubiquinone. Couples the redox reaction to proton translocation (for every two electrons transferred, four hydrogen ions are translocated across the cytoplasmic membrane), and thus conserves the redox energy in a proton gradient.
Participates actively in the response to hyperosmotic and heat shock by preventing the aggregation of stress-denatured proteins, in association with DnaK and GrpE. It is the nucleotide exchange factor for DnaK and may function as a thermosensor. 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.
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.
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.
Catalyzes the conversion of epoxyqueuosine (oQ) to queuosine (Q), which is a hypermodified base found in the wobble positions of tRNA(Asp), tRNA(Asn), tRNA(His) and tRNA(Tyr).
Participates in transcription elongation, termination and antitermination.
Belongs to the universal ribosomal protein uS19 family.
Protein S19 forms a complex with S13 that binds strongly to the 16S ribosomal RNA.
Monomer. Binds directly to the core enzyme of the DNA-dependent RNA polymerase and to nascent RNA.
Participates in both transcription termination and antitermination.
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.
Belongs to the short-chain dehydrogenases/reductases (SDR) family.
Interacts with outer membrane receptor proteins that carry out high-affinity binding and energy dependent uptake into the periplasmic space of specific substrates. It could act to transduce energy from the cytoplasmic membrane to specific energy-requiring processes in the outer membrane, resulting in the release into the periplasm of ligands bound by these outer membrane proteins.
Belongs to the glyceraldehyde-3-phosphate dehydrogenase family.
Major role in the synthesis of nucleoside triphosphates other than ATP. The ATP gamma phosphate is transferred to the NDP beta phosphate via a ping-pong mechanism, using a phosphorylated active-site intermediate.
Catalyzes the NADPH-dependent reduction of beta-ketoacyl-ACP substrates to beta-hydroxyacyl-ACP products, the first reductive step in the elongation cycle of fatty acid biosynthesis.
Belongs to the glycosyltransferase 4 family. MraY subfamily.
Catalyzes the initial step of the lipid cycle reactions in the biosynthesis of the cell wall peptidoglycan: transfers peptidoglycan precursor phospho-MurNAc-pentapeptide from UDP-MurNAc-pentapeptide onto the lipid carrier undecaprenyl phosphate, yielding undecaprenyl-pyrophosphoryl-MurNAc-pentapeptide, known as lipid I.
Belongs to the outer membrane factor (OMF) (TC 1.B.17) family.
Belongs to the universal ribosomal protein uS9 family.
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.
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 membrane fusion protein (MFP) (TC 8.A.1) family.
Transfers and isomerizes the ribose moiety from AdoMet to the 7-aminomethyl group of 7-deazaguanine (preQ1-tRNA) to give epoxyqueuosine (oQ-tRNA).
Belongs to the polypeptide deformylase family.
Removes the formyl group from the N-terminal Met of newly synthesized proteins. Requires at least a dipeptide for an efficient rate of reaction. N-terminal L-methionine is a prerequisite for activity but the enzyme has broad specificity at other positions.
Catalyzes the reversible phosphorylation of UMP to UDP.
Belongs to the bacterial ribosomal protein bS21 family.
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 FPP/GGPP synthase family.
Belongs to the bacterial ribosomal protein bL28 family.
Allosterically activated by ADP and other diphosphonucleosides, and allosterically inhibited by phosphoenolpyruvate.
Belongs to the phosphofructokinase type A (PFKA) family. ATP-dependent PFK group I subfamily. Prokaryotic clade 'B1' sub-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 universal ribosomal protein uL15 family.
Belongs to the beta sliding clamp family.
Confers DNA tethering and processivity to DNA polymerases and other proteins. Acts as a clamp, forming a ring around DNA (a reaction catalyzed by the clamp-loading complex) which diffuses in an ATP-independent manner freely and bidirectionally along dsDNA. Initially characterized for its ability to contact the catalytic subunit of DNA polymerase III (Pol III), a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria; Pol III exhibits 3'-5' exonuclease proofreading activity. The beta chain is required for initiation of replication as well as for processivity of DNA replication.
Forms a ring-shaped head-to-tail homodimer around DNA.
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.
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 thiolase-like superfamily. Beta-ketoacyl-ACP synthases family.
Involved in the type II fatty acid elongation cycle. Catalyzes the elongation of a wide range of acyl-ACP by the addition of two carbons from malonyl-ACP to an acyl acceptor. Can efficiently catalyze the conversion of palmitoleoyl-ACP (cis-hexadec-9-enoyl-ACP) to cis-vaccenoyl-ACP (cis-octadec-11-enoyl-ACP), an essential step in the thermal regulation of fatty acid composition.
Belongs to the HesB/IscA family. Ycf83 subfamily.
Catalyzes the reversible reaction in which hydroxymethyl group from 5,10-methylenetetrahydrofolate is transferred onto alpha-ketoisovalerate to form ketopantoate.
Belongs to the bacterial ribosomal protein bL9 family.
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.
Component of the F(0) channel, it forms part of the peripheral stalk, linking F(1) to F(0).
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.