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PubMed1981

Phagocytosis and degradation of DNA-anti-DNA complexes by human phagocytes II. Influence of the size of the complexes.

The influence was studied of the size of DNA-anti-DNA complexes on their capacity to induce phagocytosis and degradation by monocytes and neutrophils from human blood. An estimate of the size of the complexes was obtained by precipitation analysis, sucrose-gradient velocity sedimentation and filtration over Nucleopore filters. The results show that only those complexes are processes that precipitate in 15 min at 3000 x g. These complexes have an S value of more than 25000 and a diameter of more than 0.4 micrometer. Likewise, tetanus-anti-tetanus complexes also had to be precipitable in 15 min at 3000 x g to be processed by the phagocytes.

Antigen-Antibody Complex↗

PubMed1989

Mechanism of immune complex-mediated damage: induction of interleukin 1 by immune complexes and synergy with interferon-gamma and tumor necrosis factor-alpha.

The ability of immune complexes derived from patients with type II mixed essential cryoglobulinemia to trigger the production of interleukin 1 (IL 1) was investigated. Immune complexes containing either IgM/IgG or IgA/IgG aggregates were shown to induce IL 1 production in human peripheral blood monocyte-enriched populations. Interferon-gamma alone did not induce detectable IL 1, but increased the IL 1 production induced by the immune complexes. Tumor necrosis factor-alpha, which is a potent inducer of IL 1, also enhanced IL 1 production following stimulation with suboptimal doses of the immune complex. The findings suggest that immune complexes may induce inflammation partly due to their capacity to induce the synthesis of IL 1.

Antigen-Antibody Complex↗

PubMed1996

Epitope mapping and reactivity of autoantibodies to the E2 component of 2-oxoglutarate dehydrogenase complex in primary biliary cirrhosis using recombinant 2-oxoglutarate dehydrogenase complex.

Five different target mitochondrial autoantigens recognized by sera from patients with primary biliary cirrhosis (PBC) have been identified as subunits of the following 2-oxo acid dehydrogenase complexes: the pyruvate dehydrogenase complex (PDC), the branched chain 2-oxo acid dehydrogenase complex (BCOADC), and the 2-oxoglutarate dehydrogenase complex (OGDC). Unlike the E2 subunits of PDC (PDC-E2) and BCOADC (BCOADC-E2), the E2 subunits of OGDC (OGDC-E2) reactivity of PBC sera and the reactive epitope of OGDC-D2 have not hitherto been studied in detail. In this report, we took advantage of a recombinant fusion protein for OGDC-E2 to address these issues. Eighty of 268 (29.9%) PBC patient sera but none of the 45 controls reacted with recombinant OGDC-E2. The recombinant OGDC-E2 was judged to express the immunodominant epitope, because when sera from patients with PBC were preabsorbed with the recombinant fusion protein, such sera were depleted of reactivity against 48 kD OGDC-E2 when probed on beef heart mitochondria (BHM) but retained reactivity toward PDC-E2 and/or BCOADC-E2. Furthermore, affinity-purified PBC sera against recombinant OGDC-E2 reacted only with native OGDC-E2 and not with any other enzyme components of the 2-oxo acid dehydrogenase complex. Antimitochondrial autoantibodies (AMA) against OGDC-E2 included immunoglobulin (Ig)G2, IgG3 and IgM and the relative titers were as follows: IgG2 > IgG3 > IgM. Finally, using overlapping recombinant polypeptides, it was determined that a minimum of 81 amino acids (residues 67-147) corresponding to the lipoyl domain of OGDC-E2 are necessary for reactivity, suggesting that a conformational autoepitope is recognized by AMA. These data suggest that each of the 2-oxo acid dehydrogenase enzymes has distinct antigenicity despite their similarities in structure and function. The availability of recombinant OGDC-E2 autoantigen will allow the design of additional studies to further our understanding of the role of mitochondrial autoantigens in the pathogenesis of PBC.

Animals↗

PubMed1992

Major histocompatibility complex, t-complex, and leukemia.

In experimental models, leukemia was the first disease shown to have an association with the major histocompatibility complex (MHC) genes. In humans, several allelic human-leukocyte antigen (HLA) associations also have been recognized. In addition to allelic associations, atypical HLA segregation patterns have been observed in leukemic families. These include a higher frequency of HLA-identical unaffected siblings, increased HLA homozygosity and increased maternal HLA-DR identity. These observations suggest preferential transmission of disease-associated haplotypes and a male transmission bias in leukemic families. The lack of disease-specific segregation, however, supports the idea that the HLA system is not directly relevant in leukemogenesis. Therefore, the existence of another genetic region linked to the MHC, causing segregation distortion, and containing recessive leukemia susceptibility genes may be postulated. The mouse t-complex would fit this model. This gene complex has recessive (semi-) lethal genes, is transmitted preferentially through fathers, and both the mouse t-complex and its rat homolog, growth and reproduction complex grc, confer susceptibility to carcinogenesis. This model could also explain the increased spontaneous abortion rate in mothers of leukemic patients, epidemiologic associations of leukemia with oral clefts and neuroectodermal tumors, and the transmission of a radiation-induced leukemia risk through fathers. Such segregation distortion might be the reason behind the maintenance of a gene(s) with a lethal effect in the population.

Animals↗

PubMed1983

Localization of horseradish peroxidase (HRP)-anti-HRP complexes in cryostat sections: influence of endotoxin on trapping of immune complexes in the spleen of the rat.

Cryostat sections of the rat spleen were incubated with a medium containing horseradish peroxidase (HRP)-anti-HRP complexes. After this incubation HRP-anti-HRP complexes were demonstrated in the follicle centres in the splenic white pulp. The localization pattern of the HRP-anti-HRP complexes after incubation ("in-vitro trapping") was compared with the localization pattern of 125I BSA-anti-BSA complexes after intravenous injection ("in-vivo trapping"). Furthermore, the influence of endotoxin on the "in-vitro trapping" was studied. The "in-vitro trapping" was representative of the second, retaining phase of the "in-vivo trapping". Evidence is presented that endotoxin inhibits trapping of immune complexes by a direct effect on the follicular dendritic cell.

Animals↗

PubMed1991

Endocytosis of the TCR/CD3 complex and the class-I major histocompatibility complex in a human T cell line.

We investigated the expression of the T cell receptor (TCR)/CD3 complex on a CD4-positive human T cell lymphoma cell line treated with phorbol myristate acetate (PMA) and/or CA2+ ionophore using fluorescence flow cytometry and fluorescence microscopic analysis. PMA induced a significant decrease in the expression of the CD3 complex on the cell membranes. Fluorescence microscopy confirmed that the down regulation is due to internalization of the antigens. Ca2+ ionophore treatment had no effect on the internalization of the CD3 complex. Double staining revealed that the vesicles containing the internalized CD3 complex and those containing intra-cytoplasmic class I major histocompatibility complex antigen had similar distribution in the PMA-stimulated cells, implying coexistence of these two antigens in a cytoplasmic perinuclear distribution.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1992

Deletion of subunit 9 of the Saccharomyces cerevisiae cytochrome bc1 complex specifically impairs electron transfer at the ubiquinol oxidase site (center P) in the bc1 complex.

Deletion of QCR9, the nuclear gene encoding subunit 9 of the mitochondrial cytochrome bc1 complex in Saccharomyces cerevisiae, results in inactivation of the bc1 complex and inability of the yeast to grow on non-fermentable carbon sources. The loss of bc1 complex activity is due to loss of electron transfer activity at the ubiquinol oxidase site (center P) in the complex. Electron transfer at the ubiquinone reductase site (center N), is unaffected by the loss of subunit 9, but the extent of cytochrome b reduction is diminished. This is the first instance in which a supernumerary polypeptide, lacking a redox prosthetic group, has been shown to be required for an electron transfer reaction within the cytochrome bc1 complex.

Cytochrome b Group↗

PubMed1983

Precipitability and composition of HBsAg-anti-HBs immune complexes formed in the presence of complement. A model of circulating immune complex analysis.

Immune complexes (IC) of partially purified HBsAg and human anti-HBs were prepared at different antigen/antibody ratios in the presence of complement in normal human serum (NHS), and under conditions not allowing complement activation in buffers or in NHS containing 10 mM EDTA (NHS-EDTA). Commercial preparations of the radiolabelled antigen and antibody were used. IC formed in NHS were not significantly precipitated even after incubation for 24 h at 4 degrees C, whereas a typical precipitation curve was observed with complexes formed in the absence of complement. Thus, complement activation was found to markedly and permanently inhibit precipitability of HBsAg-anti-HBs immune complexes (HBsAg-IC). HBsAg-IC were precipitated from sera with 3.5% polyethylene glycol (PEG), boiled in sodium dodecyl sulphate (SDS)-urea buffer, and analysed by SDS-polyacrylamide slab gel electrophoresis (SDS-PAGE). With complexes formed in the presence of complement, about one-sixth of the antibody activity was found in high molecular weight fractions corresponding in size to IgG oligomers. By contrast, with complexes formed without complement, no significant amount of antibody was found in these fractions. With blotting technique and radiolabelled anti-human-C3 antibody, it was demonstrated that anti-HBs was covalently bound to C3b fragments in IC formed in the presence of complement and was in the high molecular weight fractions.

Animals↗

PubMed1983

Purification and immunochemical studies of pyruvate dehydrogenase complex from rat heart, and cell-free synthesis of lipoamide dehydrogenase, a component of the complex.

Pyruvate dehydrogenase complex was purified from rat heart. The complex showed four polypeptide bands on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, corresponding to lipoate acetyltransferase (mol.wt. 68 000), lipoamide dehydrogenase (mol.wt. 56 000), alpha-subunit (mol.wt. 41 000) and beta-subunit (mol.wt. 35 000) of pyruvate dehydrogenase. Rat heart pyruvate dehydrogenase complex was dissociated into three component enzymes and the antibodies against each component enzyme were prepared. Anti-pyruvate dehydrogenase and anti-lipoate acetyltransferase antibodies effectively precipitated pyruvate dehydrogenase complex, but an anti-lipoamide dehydrogenase antibody released lipoamide dehydrogenase from the complex and effectively precipitated lipoamide dehydrogenase. Lipoamide dehydrogenase was synthesized in a cell-free reticulocyte lysate system with total RNA from rat liver. Its translation product was detected as a putative precursor which is 3000 Da larger than the mature subunit. In cell-free translation programmed with free and membrane-bound polysomes, activity of mRNA coding for the precursor of the enzyme was much higher in free polysomes than in membrane-bound polysomes.

Animals↗

PubMed2006

Tight binding of NADPH to the 39-kDa subunit of complex I is not required for catalytic activity but stabilizes the multiprotein complex.

In addition to the 14 central subunits, respiratory chain complex I from the aerobic yeast Yarrowia lipolytica contains at least 24 accessory subunits, most of which are poorly characterized. Here we investigated the role of the accessory 39-kDa subunit which belongs to the heterogeneous short-chain dehydrogenase/reductase (SDR) enzyme family and contains non-covalently bound NADPH. Deleting the chromosomal copy of the gene that codes for the 39-kDa subunit drastically impaired complex I assembly in Y. lipolytica. We introduced several site-directed mutations into the nucleotide binding motif that severely reduced NADPH binding. This effect was most pronounced when the arginine at the end of the second beta-strand of the NADPH binding Rossman fold was replaced by leucine or aspartate. Mutations affecting nucleotide binding had only minor or moderate effects on specific catalytic activity in mitochondrial membranes but clearly destabilized complex I. One mutant exhibited a temperature sensitive phenotype and significant amounts of three different subcomplexes were observed even at more permissive temperature. We concluded that the 39-kDa subunit of Y. lipolytica plays a critical role in complex I assembly and stability and that the bound NADPH serves to stabilize the subunit and complex I as a whole rather than serving a catalytic function.

Amino Acid Sequence↗

PubMed2003

Sperm motility-activating complex formed by t-complex distorters.

Transmission ratio distortion is a dramatic example of non-Mendelian transmission. In mice, t-haplotype males produce dysfunctional +-sperm and normal t-sperm, leading to transmission in favor of t-sperm. Genetic studies have indicated that the t-complex responder locus, Tcr, rescues t-sperm but not +-sperm from defective products of t-complex distorter loci, Tcds. Light chain 1 (LC1) and LC3 from sea urchin sperm outer arm dynein have sequence similarities to Tctex2 and Tctex1, respectively, both of which are wild-type products of Tcds. We show here that LC1 and LC3 are able to make a 1:1 complex. Since Tcr is a member of the Smok (sperm motility kinase) family and LC1 is phosphorylated at the activation of sperm motility in a cAMP-dependent manner, this complex in a dynein motor molecule might be a direct target of Smok/Tcr kinase in a signal cascade that regulates sperm motility. Thus, we designate it as Smoac (sperm motility activating complex).

Amino Acid Sequence↗

PubMed2006

Characterization of synthetic oxomanganese complexes and the inorganic core of the O2-evolving complex in photosystem II: evaluation of the DFT/B3LYP level of theory.

The capabilities and limitations of the Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional are investigated as applied to studies of mixed-valent multinuclear oxomanganese complexes. Benchmark calculations involve the analysis of structural, electronic and magnetic properties of di-, tri- and tetra-nuclear Mn complexes, previously characterized both chemically and spectroscopically, including the di-mu-oxo bridged dimers [Mn(III)Mn(IV)(mu-O)(2)(H(2)O)(2)(terpy)(2)](3+) (terpy=2,2':6,2''-terpyridine) and [Mn(III)Mn(IV)(mu-O)(2)(phen)(4)](3+) (phen=1,10-phenanthroline), the Mn trimer [Mn(3)O(4)(bpy)(4)(H(2)O)(2)](4+) (bpy=2,2'-bipyridine), and the tetramer [Mn(4)O(4)L(6)](+) with L=Ph(2)PO(2)(-). Furthermore, the density functional theory (DFT) B3LYP level is applied to analyze the hydrated Mn(3)O(4)CaMn cluster completely ligated by water, OH(-), Cl(-), carboxylate and imidazole ligands, analogous to the '3+1 Mn tetramer' of the oxygen-evolving complex of photosystem II. It is found that DFT/B3LYP predicts structural and electronic properties of oxomanganese complexes in pre-selected spin-electronic states in very good agreement with X-ray and magnetic experimental data, even when applied in conjunction with rather modest basis sets. However, it is conjectured that the energetics of low-lying spin-states is beyond the capabilities of the DFT/B3LYP level, constituting a limitation to mechanistic studies of multinuclear oxomanganese complexes where until now the performance of DFT/B3LYP has raised little concern.

Biomimetics↗

PubMed2004

Crystal structure of Mycoplasma arthritidis mitogen complexed with HLA-DR1 reveals a novel superantigen fold and a dimerized superantigen-MHC complex.

Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing particular TCR Vbeta elements. Here we report the crystal structure of MAM complexed with a major histocompatibility complex (MHC) antigen, HLA-DR1, loaded with haemagglutinin peptide 306-318 (HA). The structure reveals that MAM has a novel fold composed of two alpha-helical domains. This fold is entirely different from that of the pyrogenic superantigens, consisting of a beta-grasped motif and a beta barrel. In the complex, the N-terminal domain of MAM binds orthogonally to the MHC alpha1 domain and the bound HA peptide, and to a lesser extent to the MHC beta1 domain. Two MAM molecules form an asymmetric dimer and cross-link two MHC antigens to form a plausible, dimerized MAM-MHC complex. These data provide the first crystallographic evidence that superantigens can dimerize MHC molecules. Based on our structure, a model of the TCR2MAM2MHC2 complex is proposed.

Antigens↗

PubMed2003

The conserved Nup107-160 complex is critical for nuclear pore complex assembly.

Nuclear pore complexes (NPCs) are large multiprotein assemblies that allow traffic between the cytoplasm and the nucleus. During mitosis in higher eukaryotes, the Nuclear Envelope (NE) breaks down and NPCs disassemble. How NPCs reassemble and incorporate into the NE upon mitotic exit is poorly understood. We demonstrate a function for the conserved Nup107-160 complex in this process. Partial in vivo depletion of Nup133 or Nup107 via RNAi in HeLa cells resulted in reduced levels of multiple nucleoporins and decreased NPC density in the NE. Immunodepletion of the entire Nup107-160 complex from in vitro nuclear assembly reactions produced nuclei with a continuous NE but no NPCs. This phenotype was reversible only if Nup107-160 complex was readded before closed NE formation. Depletion also prevented association of FG-repeat nucleoporins with chromatin. We propose a stepwise model in which postmitotic NPC assembly initiates on chromatin via early recruitment of the Nup107-160 complex.

Animals↗

PubMed1996

Protein-protein interactions in the pyruvate dehydrogenase multienzyme complex: dihydrolipoamide dehydrogenase complexed with the binding domain of dihydrolipoamide acetyltransferase.

BACKGROUND: The ubiquitous pyruvate dehydrogenase multienzyme complex is built around an octahedral or icosahedral core of dihydrolipoamide acetyltransferase (E2) chains, to which multiple copies of pyruvate decarboxylase (E1) and dihydrolipoamide dehydrogenase (E3) bind tightly but non-covalently. E2 is a flexible multidomain protein that mediates interactions with E1 and E3 through a remarkably small binding domain (E2BD). RESULTS: In the Bacillus stearothermophilus complex, the E2 core is an icosahedral assembly of 60 E2 chains. The crystal structure of the E3 dimer (101 kDa) complexed with E2BD (4 kDa) has been solved to 2.6 A resolution. Interactions between E3 and E2BD are dominated by an electrostatic zipper formed by Arg135 and Arg139 in the N-terminal helix of E2BD and Asp344 and Glu431 of one of the monomers of E3. E2BD interacts with both E3 monomers, but the binding site is located close to the twofold axis. Thus, in agreement with earlier biochemical results, it is impossible for two molecules of E2BD to bind simultaneously to one E3 dimer. CONCLUSIONS: Combining this new structure for the E3-E2BD complex with previously determined structures of the E2 catalytic domain and the E2 lipoyl domain creates a model of the E2 core showing how the lipoyl domain can move between the active sites of E2 and E3 in the multienzyme complex.

Acetyltransferases↗

PubMed1992

Induced peptide conformations in different antibody complexes: molecular modeling of the three-dimensional structure of peptide-antibody complexes using NMR-derived distance restraints.

Intramolecular interactions in bound cholera toxin peptide (CTP3) in three antibody complexes were studied by two-dimensional transferred NOE spectroscopy. These measurements together with previously recorded spectra that show intermolecular interactions in these complexes were used to obtain restraints on interproton distances in two of these complexes (TE32 and TE33). The NMR-derived distance restraints were used to dock the peptide into calculated models for the three-dimensional structure of the antibody combining site. It was found that TE32 and TE33 recognize a loop comprising the sequence VPGSQHID and a beta-turn formed by the sequence VPGS. The third antibody, TE34, recognizes a different epitope within the same peptide and a beta-turn formed by the sequence IDSQ. Neither of these two turns was observed in the free peptide. The formation of a beta-turn in the bound peptide gives a compact conformation that maximizes the contact with the antibody and that has greater conformational freedom than alpha-helix or beta-sheet secondary structure. A total of 15 antibody residues are involved in peptide contacts in the TE33 complex, and 73% of the contact area in the antibody combining site consists of the side chains of aromatic amino acids. A comparison of the NMR-derived models for CTP3 interacting with TE32 and TE33 with the previously derived model for TE34 reveals a relationship between amino acid sequence and combining site structure and function. (a) The three aromatic residues that interact with the peptide in TE32 and TE33 complexes, Tyr 32L, Tyr 32H, and Trp 50H, are invariant in all light chains sharing at least 65% identity with TE33 and TE32 and in all heavy chains sharing at least 75% identity with TE33. Although TE34 differs from TE32 and TE33 in its fine specificity, these aromatic residues are conserved in TE34 and interact with its antigen. Therefore, we conclude that the role of these three aromatic residues is to participate in nonspecific hydrophobic interactions with the antigen. (b) Residues 31, 31c, and 31e of CDR1 of the light chain interact with the antigen in all three antibodies that we have studied. The amino acids in these positions in TE34 differ from those in TE32 and TE33, and they are involved in specific polar interactions with the antigen. (c) CDR3 of the heavy chain varies considerably both in length and in sequence between TE34 and the two other anti-CTP3 antibodies. These changes modify the shape of the combining site and the hydrophobic and polar interactions of CDR3 with the peptide antigen.

Amino Acid Sequence↗

PubMed2001

Three-dimensional structure of ATP:corrinoid adenosyltransferase from Salmonella typhimurium in its free state, complexed with MgATP, or complexed with hydroxycobalamin and MgATP.

In Salmonella typhimurium, formation of the cobalt-carbon bond in the biosynthetic pathway for adenosylcobalamin is catalyzed by the product of the cobA gene which encodes a protein of 196 amino acid residues. This enzyme is an ATP:co(I)rrinoid adenosyltransferase which transfers an adenosyl moiety from MgATP to a broad range of co(I)rrinoid substrates that are believed to include cobinamide, its precursor cobyric acid and probably others as yet unidentified, and hydroxocobalamin. Three X-ray structures of CobA are reported here: its substrate-free form, a complex of CobA with MgATP, and a ternary complex of CobA with MgATP and hydroxycobalamin to 2.1, 1.8, and 2.1 A resolution, respectively. These structures show that the enzyme is a homodimer. In the apo structure, the polypeptide chain extends from Arg(28) to Lys(181) and consists of an alpha/beta structure built from a six-stranded parallel beta-sheet with strand order 324516. The topology of this fold is very similar to that seen in RecA protein, helicase domain, F(1)ATPase, and adenosylcobinamide kinase/adenosylcobinamide guanylyltransferase where a P-loop is located at the end of the first strand. Strikingly, the nucleotide in the MgATP.CobA complex binds to the P-loop of CobA in the opposite orientation compared to all the other nucleotide hydrolases. That is, the gamma-phosphate binds at the location normally occupied by the alpha-phosphate. The unusual orientation of the nucleotide arises because this enzyme transfers an adenosyl group rather than the gamma-phosphate. In the ternary complex, the binding site for hydroxycobalamin is located in a shallow bowl-shaped depression at the C-terminal end of the beta-sheet of one subunit; however, the active site is capped by the N-terminal helix from the symmetry-related subunit that now extends from Gln(7) to Ala(24). The lower ligand of cobalamin is well-ordered and interacts mostly with the N-terminal helix of the symmetry-related subunit. Interestingly, there are few interactions between the protein and the polar side chains of the corrin ring which accounts for the broad specificity of this enzyme. The corrin ring is oriented such that the cobalt atom is located approximately 6.1 A from C5' of the ribose and is beyond the range of nucleophilic attack. This suggests that a conformational change occurs in the ternary complex when Co(III) is reduced to Co(I).

Adenosine Triphosphate↗

PubMed2004

Amino-terminal residues 1-45 of the Escherichia coli pyruvate dehydrogenase complex E1 subunit interact with the E2 subunit and are required for activity of the complex but not for reductive acetylation of the E2 subunit.

While N-terminal amino acids 1-55 are not seen in the structure of the Escherichia coli pyruvate dehydrogenase complex E1 subunit (PDHc-E1), mass spectrometric analysis indicated that this amino-terminal region of PDHc-E1 was protected by PDHc-E2. Hence, five deletion constructs of PDHc-E1 were created, Delta6-15, Delta16-25, Delta26-35, Delta36-45, and Delta46-55, along with single-site substitutions at Asp7, Asp9, Pro10, Ile11, Glu12, Thr13, Arg14, and Asp15. The decarboxylation of pyruvate and the ability of PDHc-E1 to dimerize are not affected by any of the deletions or substitutions. While Delta46-55 and the Pro10Ala, Ile11Ala, and Thr13Ala variants could form a complex with PDHc-E2, and produced NADH in the overall assay, Delta16-25, Delta26-35, and Delta36-45 and the Asp7Ala, Asp9Ala, Glu12Gln, Glu12Asp, Arg14Ala, and Asp15Ala variants failed in both respects. Remarkably, all constructs of PDHc-E1 from E. coli, as well as PDHc-E1 from Mycobacterium tuberculosis, could carry out reductive acetylation of the E. coli lipoyl domain, but only constructs of the E. coli PDHc-E1 could reductively acetylate E. coli PDHc-E2. It was concluded that there are at least two loci of interaction between the PDHc-E1 and PDHc-E2 subunits: (1) the thiamin diphosphate-bound substrate on PDHc-E1 and the lipoylamide of PDHc-E2, as reflected by the ability to reductively acetylate the latter; and (2) amino terminal residues 1-45 of PDHc-E1 with regions of PDHc-E2 (so far undefined for the E. coli complex), as reflected by the overall activity of the entire complex. These studies add important information regarding recognition within this multienzyme complex class with an alpha(2) E1 assembly.

Acetylation↗