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PubMed1998

GPR1 encodes a putative G protein-coupled receptor that associates with the Gpa2p Galpha subunit and functions in a Ras-independent pathway.

The yeast RAS1 and RAS2 genes appear to be involved in control of cell growth in response to nutrients. Here we show that this growth control also involves a signal mediated by the heterotrimeric G protein alpha subunit homolog encoded by GPA2. A GPA2 null allele conferred a severe growth defect on cells containing a null allele of RAS2, although either mutation alone had little effect on growth rate. A constitutive allele of GPA2 could stimulate growth of a strain lacking both RAS genes. Constitutive GPA2 conferred heat shock sensitivity on both wild-type cells and cells lacking RAS function, but had no effect in a strain containing a null allele of SCH9, which encodes a kinase related to protein kinase A. The GPR1 gene was isolated and was found to encode a protein with the characteristics of a G protein-coupled receptor. Double Deltagpr1 Deltaras2 mutants displayed a severe growth defect that was suppressed by expression of the constitutive allele of GPA2, confirming that GPR1 acts upstream of GPA2. Gpr1p is expressed on the cell surface and requires sequences in the membrane-proximal region of its third cytoplasmic loop for function, as expected for a G protein-coupled receptor. GPR1 RNA was induced when cells were starved for nitrogen and amino acids. These results are consistent with a model in which the GPR1/GPA2 pathway activates the Sch9p kinase to generate a response that acts in parallel with that generated by the Ras/cAMP pathway, resulting in the integration of nutrient signals.

Amino Acid Sequence↗
PubMed2004

Tertiary structure predictions on a comprehensive benchmark of medium to large size proteins.

We evaluate tertiary structure predictions on medium to large size proteins by TASSER, a new algorithm that assembles protein structures through rearranging the rigid fragments from threading templates guided by a reduced Calpha and side-chain based potential consistent with threading based tertiary restraints. Predictions were generated for 745 proteins 201-300 residues in length that cover the Protein Data Bank (PDB) at the level of 35% sequence identity. With homologous proteins excluded, in 365 cases, the templates identified by our threading program, PROSPECTOR_3, have a root-mean-square deviation (RMSD) to native < 6.5 angstroms, with >70% alignment coverage. After TASSER assembly, in 408 cases the best of the top five full-length models has a RMSD < 6.5 angstroms. Among the 745 targets are 18 membrane proteins, with one-third having a predicted RMSD < 5.5 A. For all representative proteins less than or equal to 300 residues that have corresponding multiple NMR structures in the Protein Data Bank, approximately 20% of the models generated by TASSER are closer to the NMR structure centroid than the farthest individual NMR model. These results suggest that reasonable structure predictions for nonhomologous large size proteins can be automatically generated on a proteomic scale, and the application of this approach to structural as well as functional genomics represent promising applications of TASSER.

Algorithms↗
PubMed2002

HLA associations with HBV carriage and proteinuria.

Human leucocyte antigen (HLA) associations have been reported in children with hepatitis B virus (HBV) associated membranous nephropathy (MN). In a previous study, we found an association with HLA DQB1*0603 in black children with HBVMN. To determine whether HLA DQB1*0603 predisposes to HBV carriage and development of abnormal proteinuria, we studied 70 family members of 14 children with HBVMN positive for HLA DQB1*0603. HBV was determined using third generation ELISA, slot-blot hybridisation, and nested polymerase chain reaction. HLA class I antigens were determined using a two-staged lymphocytotoxic test whereas class II antigen typing was done using sequence-specific primers. Abnormal proteinuria was defined by a protein/creatinine ratio > or =0.2. Associations of HLA DQB1*0603 with HBV carriage and abnormal proteinuria were determined using the mean probability ratio (LOD scores). Forty-seven (67%) family members were positive for HBV infection. Nineteen (27%) had abnormal range proteinuria. LOD scores in the study subjects with DQB1*0603 who were HBV negative versus those with DQB1*0603 who were HBV positive was not significant (anti-log sum =2.0559 and average 0.23). When a similar calculation was made for abnormal proteinuria, there were no significant findings (anti-log sum =3.8587 and average 0.43). This lack of association of HLA DQB1*0603 with either HBV carriage or abnormal proteinuria in family members suggests that additional factors may play a role in predisposing children to chronic HBV carriage and the development of MN. We therefore conclude that the main effect of HLA DQB1*0603 that distinguishes family members from HBVMN is the degree of proteinuria, which is a reflection of the severity of glomerular basement membrane damage in the latter.

Adolescent↗
PubMed1992

Nucleotide sequence analysis of human hypoxanthine phosphoribosyltransferase (HPRT) gene deletions.

We have determined the nucleotide sequences of 10 intragenic human HPRT gene deletion junctions isolated from thioguanine-resistant PSV811 Werner syndrome fibroblasts or from HL60 myeloid leukemia cells. Deletion junctions were located by fine structure blot hybridization mapping and then amplified with flanking oligonucleotide primer pairs for DNA sequence analysis. The junction region sequences from these 10 HPRT mutants contained 13 deletions ranging in size from 57 bp to 19.3 kb. Three DNA inversions of 711, 368, and 20 bp were associated with tandem deletions in two mutants. Each mutant contained the deletion of one or more HPRT exon, thus explaining the thioguanine-resistant cellular phenotype. Deletion junction and donor nucleotide sequence alignments suggest that all of these HPRT gene rearrangements were generated by the nonhomologous recombination of donor DNA duplexes that share little nucleotide sequence identity. This result is surprising, given the potential for homologous recombination between copies of repeated DNA sequences that constitute approximately a third of the human HPRT locus. No difference in deletion structure or complexity was observed between deletions isolated from Werner syndrome or from HL60 mutants. This suggests that the Werner syndrome deletion mutator uses deletion mutagenesis pathway(s) that are similar or identical to those used in other human somatic cells.

Base Sequence↗
PubMed2004

Results from screening over 9000 mutation-bearing mice for defects in the electroretinogram and appearance of the fundus.

Random mutagenesis combined with phenotypic screening using carefully crafted functional tests has successfully led to the discovery of genes that are essential for a number of functions. This approach does not require prior knowledge of the identity of the genes that are involved and is a way to ascribe function to the nearly 6000 genes for which knowledge of the DNA sequence has been inadequate to determine the function of the gene product. In an effort to identify genes involved in the visual system via this approach, we have tested over 9000 first and third generation offspring of mice treated with the mutagen N-ethyl-N-nitrosourea (ENU) for visual defects, as evidenced by abnormalities in the electroretinogram and appearance of the fundus. We identified 61 putative mutations with this procedure and outline the steps needed to identify the affected genes.

Animals↗
PubMed1997

Identification of a genomic locus containing three slow myosin heavy chain genes in the chicken.

Two unique cDNA clones containing chicken slow myosin heavy chain (MyHC) inserts have been isolated from an expression library. Immunochemical analyses of the expressed proteins using different slow MyHC specific monoclonal antibodies were consistent with the two clones encoding slow MyHC 1 (SM1) and slow MyHC 2 (SM2) protein sequences. Northern blot analyses showed that the clones hybridized with 6-kb mRNAs that are differentially expressed in developing and adult slow muscles, further supporting the conclusion that these two clones represent SM1 and SM2 cDNAs. Sequence analyses show that both clones encode the highly conserved light meromyosin portion of the sarcomeric myosin rod and are 78-81% homologous to a mammalian slow/cardiac beta-MyHC cDNA. Hybridization using PCR generated probes specific for SM1 and SM2 sequences demonstrated that the genes encoding these two slow MyHCs colocalized to an 80-kb BssHII genomic fragment. We further show that a probe specific to a third slow MyHC gene also hybridized with the same 80-kb genomic fragment. We conclude that in the chicken genome there is a slow MyHC locus containing at least three distinct slow MyHC genes.

Amino Acid Sequence↗
PubMed1990

Immunoglobulin heavy-chain-associated amyloidosis.

Immunoglobulin- or multiple myeloma-associated amyloidosis has been distinguished by the tissue deposition of Congophilic, fibrillar protein consisting of light chains or light-chain fragments (AL amyloidosis). We now report the isolation and characterization of another form of immunoglobulin-associated amyloid obtained from a patient who had extensive systemic amyloidosis and in whom the amyloid deposits consisted not of light chains but rather of an unusual form of heavy chain. This component, isolated from splenic amyloid extracts, represented an internally deleted IgG1 heavy chain as evidenced by immunochemical, electrophoretic, and amino acid sequence analyses. A comparable immunoglobulin-related monoclonal protein, consisting only of IgG heavy chains, was present in the patient's urine. Based on serologic reactivity with a battery of anti-immunoglobulin antisera, these two immunoglobulin-related components were antigenically identical; however, when compared to normal IgG, both were deficient in Fc-associated gamma-chain determinants. The structural abnormality of the amyloid gamma-chain protein was further evidenced by SDS/PAGE and immuno-blotting analyses: An unusually low molecular mass of approximately 22 kDa was found for this material vs. the expected value of approximately 55 kDa for a normal gamma heavy chain. Despite the lack of certain Fc determinants, the amyloid and urinary heavy-chain proteins expressed the IgG1 subclass allotype marker G1m(a) located on the third constant region (CH3) domain of the internally deleted IgG1 heavy chains. That the amyloid protein contained an intact CH3 domain was established through amino acid sequence analyses of cyanogen bromide fragments and peptides generated by a lysine-specific protease. These studies also revealed that the gamma-chain amyloid protein contained the complete heavy-chain variable (VH) domain [including the diversity (DH) and joining (JH) segments] that was contiguous with the CH3 domain. The low molecular mass of the protein resulted from the total absence of the first (CH1), hinge, and second (CH2) heavy-chain constant regions. Such extensive CH deletions and the presence of a complete VH distinguish this amyloid-associated heavy chain from all other heretofore characterized gamma-heavy-chain disease proteins. This heavy-chain-related form of immunoglobulin-associated amyloidosis is tentatively designated AH amyloidosis.

Aged↗
PubMed1989

The major dopamine D2 receptor: molecular analysis of the human D2A subtype.

The structural diversity of the human D2 dopamine receptor was examined at the nucleic acid level. Sequence analysis of receptor cDNA clones isolated from human brain and pituitary libraries and polymerase chain reaction (PCR) analysis of rat brain RNA and human genomic DNA demonstrate the presence of a predominant D2 subtype, D2A. The D2A subtype differs from the D2B subtype, previously described in rat brain RNA, in that an additional 29 amino acids are present in the putative third cytoplasmic domain, a region thought to be important for coupling to different G-proteins. The demonstration of intron sequences flanking the DNA encoding the 29-amino-acid insertion suggests that the generation of two distinct D2 dopamine receptor subtypes may arise from alternative splicing of a common genomic sequence.

Amino Acid Sequence↗
PubMed1997

2006 expressed-sequence tags derived from human chromosome 7-enriched cDNA libraries.

The establishment and mapping of gene-specific DNA sequences greatly complement the ongoing efforts to map and sequence all human chromosomes. To facilitate our studies of human chromosome 7, we have generated and analyzed 2006 expressed-sequence tags (ESTs) derived from a collection of direct selection cDNA libraries that are highly enriched for human chromosome 7 gene sequences. Similarity searches indicate that approximately two-thirds of the ESTs are not represented by sequences in the public databases, including those in dbEST. In addition, a large fraction (68%) of the ESTs do not have redundant or overlapping sequences within our collection. Human DNA-specific sequence-tagged sites (STSs) have been developed from 190 of the ESTs. Remarkably, 180 (96%) of these STSs map to chromosome 7, demonstrating the robustness of chromosome enrichment in constructing the direct selection cDNA libraries. Thus far, 140 of these EST-specific STSs have been assigned unequivocally to YAC contigs that are distributed across the chromosome. Together, these studies provide > 2000 ESTs highly enriched for chromosome 7 gene sequences, 180 new chromosome 7 STSs corresponding to ESTs, and a definitive demonstration of the ability to enrich for chromosome-specific cDNAs by direct selection. Furthermore, the libraries, sequence data, and mapping information will contribute to the construction of a chromosome 7 transcript map.

Brain↗
PubMed1992

Molecular characterization of the 28- and 31-kilodalton subunits of the Legionella pneumophila major outer membrane protein.

The major outer membrane protein of Legionella pneumophila exhibits an apparent molecular mass of 100 kDa. Previous studies revealed the oligomer to be composed of 28- and 31-kDa subunits; the latter subunit is covalently bound to peptidoglycan. These proteins exhibit cross-reactivity with polyclonal anti-31-kDa protein serum. In this study, we present evidence to confirm that the 31-kDa subunit is a 28-kDa subunit containing a bound fragment of peptidoglycan. Peptide maps of purified proteins were generated following cyanogen bromide cleavage or proteolysis with staphylococcal V8 protease. A comparison of the banding patterns resulting from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed a common pattern. Selected peptide fragments were sequenced on a gas phase microsequencer, and the sequence was compared with the sequence obtained for the 28-kDa protein. While the amino terminus of the 31-kDa protein was blocked, peptide fragments generated by cyanogen bromide treatment exhibited a sequence identical to that of the amino terminus of the 28-kDa protein, but beginning at amino acid four (glycine), which is preceded by methionine at the third position. This sequence, (Gly-Thr-Met)-Gly-Pro-Val-Trp-Thr-Pro-Gly-Asn ... , confirms that these proteins have a common amino terminus. An oligonucleotide synthesized from the codons of the common N-terminal amino acid sequence was used to establish by Southern and Northern (RNA) blot analyses that a single gene coded for both proteins. With regard to the putative porin structure, we have identified two major bands at 70 kDa and at approximately 120 kDa by nonreducing SDS-PAGE. The former may represent the typical trimeric motif, while the latter may represent either a double trimer or an aggregate. Analysis of these two forms by two-dimensional SDS-PAGE (first dimensions, nonreducing; second dimensions, reducing) established that both were composed of 31- and 28-kDa subunits cross-linked via interchain disulfide bonds. These studies confirm that the novel L. pneumophila major outer protein is covalently bound to peptidoglycan via a modified 28-kDa subunit (31-kDa anchor protein) and cross-linked to other 28-kDa subunits via interchain disulfide bonds.

Amino Acid Sequence↗
PubMed1999

Three different MHC class I molecules bind the same CTL epitope of the influenza virus in a primate species with limited MHC class I diversity.

One of the most remarkable features of the MHC class I loci of most outbred mammalian populations is their exceptional diversity, yet the functional importance of this diversity remains to be fully understood. The cotton-top tamarin (Saguinus oedipus) is unusual in having MHC class I loci that exhibit both limited polymorphism and sequence variation. To investigate the functional implications of limited MHC class I diversity in this outbred primate species, we infected five tamarins with influenza virus and defined the CTL epitopes recognized by each individual. In addition to an immunodominant epitope of the viral nucleoprotein (NP) that was recognized by all individuals, two tamarins also made a response to the same epitope of the matrix (M1) protein. Surprisingly, these two tamarins used different MHC class I molecules, Saoe-G*02 and -G*04, to present the M1 epitope. In addition, CTLs from one of the tamarins recognized target cells that expressed neither Saoe-G*02 nor -G*04, but, rather, a third MHC class I molecule, Saoe-G*12. Sequence analysis revealed that Saoe-G*12 differs from both Saoe-G*02 and -G*04 by only two nucleotides and was probably generated by recombination between these two alleles. These results demonstrate that at least three of the tamarin's MHC class I molecules can present the same epitope to virus-specific CTLs. Thus, four of the tamarin's 12 MHC class I molecules bound only two influenza virus CTL epitopes. Therefore, the functional diversity of cotton-top tamarin's MHC class I loci may be even more limited than their genetic diversity suggests.

Alleles↗
PubMed1986

Evidence for the existence of multiple alpha 1-acid glycoprotein genes in the mouse.

Three alpha 1-acid glycoprotein (AGP) cDNA clones have been isolated from a mouse liver library. Restriction enzyme mapping and sequencing of these cDNAs have shown that two, pMAGP2 and pMAGP3, are virtually identical, whereas the third, pMAGP4, differs significantly both in sequence and restriction enzyme sites. The sequences are 91% identical and differ from each other by single base differences exclusively. No frameshifts are observed, and no termination codons are generated by the single base differences. We interpret these data to indicate that there are at least two distinct AGP genes in the mouse and that two species of AGP mRNA are formed by the transcription of these genes in the liver. Based on the large number of single amino acid substitutions previously observed in human AGP (Schmid, K., Kaufmann, H., Isemura, S., Bauer, F., Emura, J., Motoyama, T., Ishiguro, M., and Nanno, S. (1973) Biochemistry 12, 2711-2724), we propose that at least two functional AGP genes may also exist in humans.

Amino Acid Sequence↗
PubMed1988

Haloperidol binding to monoclonal antibodies. Hypervariable region amino acid sequence determination.

The primary sequences of five monoclonal antibodies (mAbs A-E) which bind with various affinities (Kd = 4-810 nM) to the D-2 dopaminergic antagonist, haloperidol, have been determined. Immunoglobulin light and heavy chain mRNA was isolated and gene sequence determined by primer extension in the presence of dideoxynucleotides. The pattern of insertions and deletions found within the hypervariable regions produce loops which differ in length from one antibody to another, and are directly responsible for establishing the gross architecture of the combining site. Two of the anti-haloperidol mAbs have long hypervariable loops which form a pocket-shaped combining site. Three other mAbs have deletions of 3 or 4 amino acids in the third heavy chain complementarity producing region which result in a groove-like combining site as determined by computer based molecular modeling. A discussion of the probable mechanism by which the given sequences were generated from various gene segments is also presented.

Amino Acid Sequence↗
PubMed1995

Continuing immunoglobulin heavy chain gene rearrangements in chronic myeloid leukemia with recurrent B-lymphoid blast crises after bone marrow transplantation.

We sequentially analyzed the immunoglobulin heavy chain variable (IgH V) region gene of leukemia cells obtained from a chronic myeloid leukemia (CML) patient who had three episodes of B-lymphoid crisis after bone marrow transplantation. Southern blot analysis using the JH probe showed different rearranged bands at each crisis, although the same rearranged bands of the BCR gene were observed. We amplified and sequenced the IgH V region gene of the leukemia cells by reverse transcriptase polymerase chain reaction (RT-PCR) using the primers corresponding to the consensus 5'VH and mu constant regions. The dominant leukemia clone at each crisis had a unique VH-D-JH rearrangement; VH4A (V79)-DLR2-J5 (clone-1), VH4B (DP70)-DK4-J6 (clone-2) and VH4A (V79)-DN4-J6 (clone-3) at the first, second and third crises, respectively. Further analysis by PCR amplification using the consensus 5'VH and clone-specific primers revealed that clone-1 underwent VH4-->VH3 replacement at the second crisis, and that clone-3 was already in existence at the first crisis. Moreover, the DN4-J6 joining clone, in which the sequence was the same as that of clone-3, was identified at the first and third crises by PCR amplification using primers corresponding to the region upstream of the DN4 segment and DN4-J6 boundary of clone-3. These observations suggest that multiple clones were generated from the progenitor cells of blast crisis, which were transformed at a very early stage of B-lymphocyte ontogeny, by continuing rearrangement mechanisms of the IgH genes, and that the dominant clone at each crisis was undergoing change.

Adult↗
PubMedDate not supplied

Evidence that the recently discovered theta 1-globin gene is functional in higher primates.

A new subfamily of the alpha-globin-like family has recently been identified in higher primates, rabbit, galago and possibly the horse. One member of this subfamily, theta 1, is downstream from the adult alpha 1-globin gene. In orang-utan, but not in rabbit or galago, the theta 1-gene appears to be structurally intact, suggesting that it may be functional in this species. The orang-utan theta 1-gene possesses initiation and termination codons, and the predicted polypeptide differs from the orang-utan alpha 1-globin by 55 amino acids. The upstream promoter boxes CCAAT and ATA are present, although approximately 150 base pairs (bp) farther upstream than in the alpha 1-gene. This structural difference in the promoter between the orang-utan theta 1- and alpha 1-genes has led Proudfoot to speculate that the theta 1-gene may be inactive. We have now cloned the theta 1- and alpha 1-globin genes from the olive baboon, and have compared their sequences with those of orang-utan. The unique promoter structure of the orang-utan theta 1-gene is highly conserved in baboon, although the orang-utan and baboon diverged nearly 30 million years ago. The coding sequences of the two theta 1-genes differ by only 6.3% with 22 out of 27 nucleotide substitutions being codon third position silent changes. These data support the view that the theta 1-gene has been functional in the baboon, orang-utan, and by implication, in man. We also estimate that the duplication event generating the theta 1- and alpha-globin-like subfamilies may have occurred as much as 260 million years ago.

Amino Acid Sequence↗
PubMed2001

Use of whole genome sequence data to infer baculovirus phylogeny.

Several phylogenetic methods based on whole genome sequence data were evaluated using data from nine complete baculovirus genomes. The utility of three independent character sets was assessed. The first data set comprised the sequences of the 63 genes common to these viruses. The second set of characters was based on gene order, and phylogenies were inferred using both breakpoint distance analysis and a novel method developed here, termed neighbor pair analysis. The third set recorded gene content by scoring gene presence or absence in each genome. All three data sets yielded phylogenies supporting the separation of the Nucleopolyhedrovirus (NPV) and Granulovirus (GV) genera, the division of the NPVs into groups I and II, and species relationships within group I NPVs. Generation of phylogenies based on the combined sequences of all 63 shared genes proved to be the most effective approach to resolving the relationships among the group II NPVs and the GVs. The history of gene acquisitions and losses that have accompanied baculovirus diversification was visualized by mapping the gene content data onto the phylogenetic tree. This analysis highlighted the fluid nature of baculovirus genomes, with evidence of frequent genome rearrangements and multiple gene content changes during their evolution. Of more than 416 genes identified in the genomes analyzed, only 63 are present in all nine genomes, and 200 genes are found only in a single genome. Despite this fluidity, the whole genome-based methods we describe are sufficiently powerful to recover the underlying phylogeny of the viruses.

Animals↗
PubMed1991

The cloning and DNA sequence of the gene for the glutathione-regulated potassium-efflux system KefC of Escherichia coli.

The kefC gene of Escherichia coli encodes a potassium-efflux system that is regulated by glutathione metabolites. The close proximity of the E. coli kefC gene to the folA gene, encoding dihydrofolate reductase, has been utilized to clone the structural gene for the system from a Clarke-Carbon plasmid. The cloned gene has been refined to a region of DNA approximately 2.1 kb in length using exonuclease III-generated deletions and random MudII1734 (lacZ) insertions. The direction of transcription has been deduced from the orientation of the Mu insertions in the cloned DNA. A hybrid protein consisting of approximately two thirds of the KefC protein fused to beta-galactosidase has been shown to be membrane-located. The DNA sequence of the gene has been determined and an open reading frame of 1.86 kb has been located which could encode a protein of 620 amino acids (79010 Da). Using the T7 expression system a membrane protein, of apparent molecular mass 55-60 kDa, has been shown to be encoded by the kefC gene. The predicted protein sequence shows a highly hydrophobic amino-terminus and a strongly hydrophilic carboxy-terminus. Comparison of the amino acid sequence of the kefC gene product with those of two glutathione-utilizing enzymes, glyoxalase and dehalogenase, has revealed some similarities.

Amino Acid Sequence↗
PubMed1993

Cloning and expression of a rat acetylcholinesterase subunit: generation of multiple molecular forms and complementarity with a Torpedo collagenic subunit.

We obtained a cDNA clone encoding one type of catalytic subunit of acetylcholinesterase (AChE) from rat brain (T subunit). The coding sequence shows a high frequency of (G+C) at the third position of the codons (66%), as already noted for several AChEs, in contrast with mammalian butyrylcholinesterase. The predicted primary sequence of rat AChE presents only 11 amino acid differences, including one in the signal peptide, from that of the mouse T subunit. In particular, four alanines in the mouse sequence are replaced by serine or threonine. In northern blots, a rat AChE probe indicates the presence of major 3.2- and 2.4-kb mRNAs, expressed in the CNS as well as in some peripheral tissues, including muscle and spleen. In vivo, we found that the proportions of G1, G2, and G4 forms are highly variable in different brain areas. We did not observe any glycolipid-anchored G2 form, which would be derived from an H subunit. We expressed the cloned rat AChE in COS cells: The transfected cells produce principally an amphiphilic G1a form, together with amphiphilic G2a and G4a forms, and a nonamphiphilic G4na form. The amphiphilic G1a and G2a forms correspond to type II forms, which are predominant in muscle and brain of higher vertebrates. The cells also release G4na, G2a, and G1a in the culture medium. These experiments show that all the forms observed in the CNS in vivo may be obtained from the T subunit. By co-transfecting COS cells with the rat T subunit and the Torpedo collagenic subunit, we obtained chimeric collagen-tailed forms. This cross-species complementarity demonstrates that the interaction domains of the catalytic and structural subunits are highly conserved during evolution.

Acetylcholinesterase↗