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PubMed2000

Meiotic telomere distribution and Sertoli cell nuclear architecture are altered in Atm- and Atm-p53-deficient mice.

The ataxia telangiectasia mutant (ATM) protein is an intrinsic part of the cell cycle machinery that surveys genomic integrity and responses to genotoxic insult. Individuals with ataxia telangiectasia as well as Atm(-/-) mice are predisposed to cancer and are infertile due to spermatogenesis disruption during first meiotic prophase. Atm(-/-) spermatocytes frequently display aberrant synapsis and clustered telomeres (bouquet topology). Here, we used telomere fluorescent in situ hybridization and immunofluorescence (IF) staining of SCP3 and testes-specific histone H1 (H1t) to spermatocytes of Atm- and Atm-p53-deficient mice and investigated whether gonadal atrophy in Atm-null mice is associated with stalling of telomere motility in meiotic prophase. SCP3-H1t IF revealed that most Atm(-/-) p53(-/-) spermatocytes degenerated during late zygotene, while a few progressed to pachytene and diplotene and some even beyond metaphase II, as indicated by the presence of a few round spermatids. In Atm(-/-) p53(-/-) meiosis, the frequency of spermatocytes I with bouquet topology was elevated 72-fold. Bouquet spermatocytes with clustered telomeres were generally void of H1t signals, while mid-late pachytene and diplotene Atm(-/-) p53(-/-) spermatocytes displayed expression of H1t and showed telomeres dispersed over the nuclear periphery. Thus, it appears that meiotic telomere movements occur independently of ATM signaling. Atm inactivation more likely leads to accumulation of spermatocytes I with bouquet topology by slowing progression through initial stages of first meiotic prophase and an ensuing arrest and demise of spermatocytes I. Sertoli cells (SECs), which contribute to faithful spermatogenesis, in the Atm mutants were found to frequently display numerous heterochromatin and telomere clusters-a nuclear topology which resembles that of immature SECs. However, Atm(-/-) SECs exhibited a mature vimentin and cytokeratin 8 intermediate filament expression signature. Upon IF with ATM antibodies, we observed ATM signals throughout the nuclei of human and mouse SECs, spermatocytes I, and haploid round spermatids. ATM but not H1t was absent from elongating spermatid nuclei. Thus, ATM appears to be removed from spermatid nuclei prior to the occurrence of DNA nicks which emanate as a consequence of nucleoprotamine formation.

Animals↗
PubMed2026

Identification of a novel signature for prognostic stratification and integrative analyses in lung adenocarcinoma.

BACKGROUND: Recently, research has revealed that the Golgi apparatus is involved in the development process of cancer; however, the specific effect of Golgi apparatus-related genes (GAGs) in lung adenocarcinoma (LUAD) remains unclear. This study aims to construct a more concise and practical risk model in LUAD using GAG. METHODS: The gene expression profiles of patients with LUAD were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, and GAGs were downloaded from the Gene Set Enrichment Analysis (GSEA) database. Univariate Cox and least absolute shrinkage and selection operator (LASSO) analyses were performed to identify the prognostic GAG signature. Kaplan-Meier and receiver operating characteristic (ROC) curves were plotted to validate the predictive effect of the prognostic signatures. The correlation between the risk model and the immune landscape was examined using CIBERSORT and TIDE analyses. Also, the genes in the signature were assessed by single-cell RNA sequencing (scRNA-seq). RESULTS: A prognostic signature comprising 5 GAG genes (GNPNAT1, RGS20, CAV3, NTSR1, and FURIN) was established after LASSO and multi-Cox analyses. Both the Kaplan-Meier analysis and the ROC curves supported the strong predictive utility of the risk model. Specifically, the former yielded significant stratification in all three validation datasets (P=1.2001e-05, P=0.006, and P=0.04), while the latter provided further evidence of its predictive precision through the area under the curve. In addition, we found that the low-risk group responded better to immunotherapy than the high-risk group (P<0.0001). scRNA-seq analysis revealed the distribution patterns of the 5 GAG genes in cells. Finally, we assessed the situation of tumor mutation burden (TMB) and performed functional analysis based on the risk model of GAGs. CONCLUSIONS: The risk model based on GAGs can effectively stratify the prognosis of patients and predict immunotherapy responses in LUAD.

Golgi apparatus↗
PubMed2006

Genes that enhance the ecological fitness of Shewanella oneidensis MR-1 in sediments reveal the value of antibiotic resistance.

Environmental bacteria persist in various habitats, yet little is known about the genes that contribute to growth and survival in their respective ecological niches. Signature-tagged mutagenesis (STM) of Shewanella oneidensis MR-1 coupled with a screen involving incubations of mutant strains in anoxic aquifer sediments allowed us to identify 47 genes that enhance fitness in sediments. Gene functions inferred from annotations provide us with insight into physiological and ecological processes that environmental bacteria use while growing in sediment ecosystems. Identification of the mexF gene and other potential membrane efflux components by STM demonstrated that homologues of multidrug resistance genes present in pathogens are required for sediment fitness of nonpathogenic bacteria. Further studies with a mexF deletion mutant demonstrated that the multidrug resistance pump encoded by mexF is required for resistance to antibiotics, including chloramphenicol and tetracycline. Chloramphenicol-adapted cultures exhibited mutations in the gene encoding a TetR family regulatory protein, indicating a role for this protein in regulating expression of the mexEF operon. The relative importance of mexF for sediment fitness suggests that antibiotic efflux may be a required process for bacteria living in sediment systems.

Anti-Bacterial Agents↗
PubMed2006

Identification of a virulence-associated determinant, dihydrolipoamide dehydrogenase (lpd), in Mycoplasma gallisepticum through in vivo screening of transposon mutants.

To effectively analyze Mycoplasma gallisepticum for virulence-associated determinants, the ability to create stable genetic mutations is essential. Global M. gallisepticum mutagenesis is currently limited to the use of transposons. Using the gram-positive transposon Tn4001mod, a mutant library of 110 transformants was constructed and all insertion sites were mapped. To identify transposon insertion points, a unique primer directed outward from the end of Tn4001mod was used to sequence flanking genomic regions. By comparing sequences obtained in this manner to the annotated M. gallisepticum genome, the precise locations of transposon insertions were discerned. After determining the transposon insertion site for each mutant, unique reverse primers were synthesized based on the specific sequences, and PCR was performed. The resultant amplicons were used as unique Tn4001mod mutant identifiers. This procedure is referred to as signature sequence mutagenesis (SSM). SSM permits the comprehensive screening of the M. gallisepticum genome for the identification of novel virulence-associated determinants from a mixed mutant population. To this end, chickens were challenged with a pool of 27 unique Tn4001mod mutants. Two weeks postinfection, the birds were sacrificed, and organisms were recovered from respiratory tract tissues and screened for the presence or absence of various mutants. SSM is a negative-selection screening technique whereby those mutants possessing transposon insertions in genes essential for in vivo survival are not recovered from the host. We have identified a virulence-associated gene encoding dihydrolipoamide dehydrogenase (lpd). A transposon insertion in the middle of the coding sequence resulted in diminished biologic function and reduced virulence of the mutant designated Mg 7.

Animals↗
PubMed2005

Chromosomal aberrations involving telomeres in BRCA1 deficient human and mouse cell lines.

Cells defective in BRCA1 show genomic instability as evidenced by increased radiosensitivity, the presence of chromosomal abnormalities and the loss of heterozygosity at many loci. Reported chromosomal abnormalities in BRCA1 deficient cells include dicentric chromosomes. Dicentric chromosomes, in some cases, may arise as a result of end-to-end chromosome fusions, which represent signatures of telomere dysfunction. In this study we examined BRCA1 deficient human and mouse cells for the presence of chromosomal aberrations indicative of telomere dysfunction. We identified a lymphoblastoid cell line, GM14090, established from a BRCA1 carrier that showed elevated levels of dicentric chromosomes. Molecular cytogenetic analysis revealed that these dicentric chromosomes result from end-to-end chromosome fusions. The frequency of end-to-end chromosome fusions did not change after exposure of GM14090 cells to bleomycin but we observed elevated levels of chromosomal abnormalities involving interactions between DNA double strand breaks and uncapped telomeres in this cell line. We observed similar chromosomal abnormalities involving telomeres in the breast cancer cell line, HCC1937, homozygous for BRCA1 mutation. Finally, we analyzed mouse embryonic stem cells lacking functional Brca1 and observed the presence of telomere dysfunction following exposure of these cells to bleomycin. Our results reveal cytogenetic evidence of telomere dysfunction in BRCA1 deficient cells.

Animals↗
PubMed2026

Integration of single-cell transcriptomics and genomic mutation analysis identifies an immunotherapy-resistant tumor subcluster and validates ARNTL2 as a malignant driver in lung adenocarcinoma.

BACKGROUND: Immunotherapy resistance in lung adenocarcinoma (LUAD) remains a critical clinical challenge, and the mechanisms underlying resistance-associated intratumoral heterogeneity are poorly characterized. METHODS: We performed single-cell RNA sequencing of LUAD patients receiving neoadjuvant immunotherapy (responders vs. non-responders), integrating inferCNV, GSVA, and differential expression analyses. Cluster-specific genes were validated across seven independent cohorts (TCGA-LUAD, GSE13213, GSE26939, GSE29016, GSE30219, GSE31210, GSE42127). A multi-algorithm machine learning framework was used to construct a prognostic model, and the immune microenvironment was characterized using TCIA scoring, seven infiltration algorithms, and ESTIMATE. ARNTL2 function was assessed by CCK-8 and Transwell assays in A549 and H1299 cells. RESULTS: Non-responders showed significant enrichment of epithelial cells, depletion of cytotoxic T/NK cells, and elevated copy number variation burden versus responders (p < 0.0001). A resistance-enriched malignant subcluster (Cluster 2) exhibited hyperproliferative and metabolic reprogramming signatures with upregulated KRT17, S100A2, and CST6, which showed tumor-specific overexpression, adverse prognostic value, and genomic amplification across cohorts. CoxBoost combined with survivalSVM achieved optimal predictive performance (C-index = 0.686), yielding robust risk stratification (HR: 2.54-10.51, all p < 0.05). Low-risk patients showed greater immune infiltration and higher TCIA immunophenoscores. ARNTL2 was an independent prognostic factor (HR: 2.07-4.64) strongly correlated with risk score (r = 0.69), and its knockdown suppressed proliferation and invasion in both LUAD cell lines (all p < 0.05). CONCLUSION: This study identifies a resistance-associated malignant subcluster in LUAD, constructs a validated CoxBoost + survivalSVM prognostic model with robust immune stratification, and establishes ARNTL2 as a core oncogenic driver and therapeutic target.

ARNTL2↗
PubMed2004

Estimating the prevalence of protein sequences adopting functional enzyme folds.

Proteins employ a wide variety of folds to perform their biological functions. How are these folds first acquired? An important step toward answering this is to obtain an estimate of the overall prevalence of sequences adopting functional folds. Since tertiary structure is needed for a typical enzyme active site to form, one way to obtain this estimate is to measure the prevalence of sequences supporting a working active site. Although the immense number of sequence combinations makes wholly random sampling unfeasible, two key simplifications may provide a solution. First, given the importance of hydrophobic interactions to protein folding, it seems likely that the sample space can be restricted to sequences carrying the hydropathic signature of a known fold. Second, because folds are stabilized by the cooperative action of many local interactions distributed throughout the structure, the overall problem of fold stabilization may be viewed reasonably as a collection of coupled local problems. This enables the difficulty of the whole problem to be assessed by assessing the difficulty of several smaller problems. Using these simplifications, the difficulty of specifying a working beta-lactamase domain is assessed here. An alignment of homologous domain sequences is used to deduce the pattern of hydropathic constraints along chains that form the domain fold. Starting with a weakly functional sequence carrying this signature, clusters of ten side-chains within the fold are replaced randomly, within the boundaries of the signature, and tested for function. The prevalence of low-level function in four such experiments indicates that roughly one in 10(64) signature-consistent sequences forms a working domain. Combined with the estimated prevalence of plausible hydropathic patterns (for any fold) and of relevant folds for particular functions, this implies the overall prevalence of sequences performing a specific function by any domain-sized fold may be as low as 1 in 10(77), adding to the body of evidence that functional folds require highly extraordinary sequences.

Amino Acid Sequence↗
PubMed1999

HUA1 and HUA2 are two members of the floral homeotic AGAMOUS pathway.

The identities of the four floral organ types in an Arabidopsis flower are specified by the combinatorial activities of the floral homeotic A, B, and C function genes; AGAMOUS is the only known C function gene. We have identified two genes that interact with AG in the specification of floral structure, HUA1 and HUA2, from a screen for enhancers of a weak ag allele, ag-4. HUA1 and HUA2 are involved in all aspects of AG function. HUA2 encodes a novel protein that contains nuclear localization signals and signature motifs that suggest HUA2, like AG, may be a transcription factor. Molecular analyses suggest that HUA2 (and possibly HUA1) acts to facilitate AG action at the same hierarchical level as AG.

AGAMOUS Protein, Arabidopsis↗
PubMed2002

Cloning and molecular characterization of a SDS-activated tyrosinase from Marinomonas mediterranea.

The sequence of the tyrosinase gene cloned from Marinomonas mediterranea is reported. It is the second tyrosinase cloned from a Gram negative bacterium. Its size is higher than that of Gram positive tyrosinases from Streptomyces, and more similar to the eukaryotic enzymes. Its sequence shares the features of copper-binding sites found in all tyrosinases. Based in the comparison of tyrosinases from all types of organisms, an extension of the characteristic signatures existing at Prosite is proposed. This tyrosinase shares with some plant and amphibian tyrosinases a strong specific activation by submicellar concentrations of SDS. Intrinsic fluorescence and kinetic properties indicate that the activation is caused by an SDS-dependent conformational change that facilitates the substrate accessibility to the dicopper active site.

Amino Acid Sequence↗
PubMed2002

The "LSGGQ" motif in each nucleotide-binding domain of human P-glycoprotein is adjacent to the opposing walker A sequence.

The human multidrug resistance P-glycoprotein (P-gp, ABCB1), a member of the ATP-binding cassette (ABC) family of transport proteins, actively transports many cytotoxic compounds out of the cell. ABC transporters have two nucleotide-binding domains (NBD) and two transmembrane domains. The presence of the conserved "signature" sequence (LSGGQ) in each NBD is a unique feature in these transporters. The function of the signature sequences is unknown. In this study, we tested whether the signature sequences ((531)LSGGQ(535) in NBD1; (1176)LSGGQ(1180) in NBD2) in P-gp are in close proximity to the opposing Walker A consensus nucleotide-binding sequences ((1070)GSSGCGKS(1077) in NBD2; (427)GNSGCGKS(434) in NBD1). Pairs of cysteines were introduced into a Cys-less P-gp at the signature and "Walker A" sites and the mutant P-gps were subjected to oxidative cross-linking. At 4 degrees C, when thermal motion is low, P-gp mutants (L531C(Signature)/C1074(Walker A) and C431(Walker A)/L1176C(Signature) were cross-linked. Cross-linking inhibited the drug-stimulated ATPase activities of these two mutants. Their activities were restored, however, after addition of the reducing agent, dithiothreitol. Vanadate trapping of nucleotide at the ATP-binding sites prevented cross-linking of the mutants. These results indicate that the signature sequences are adjacent to the opposing Walker A site. They likely participate in forming the ATP-binding sites and are displaced upon ATP hydrolysis. The resulting conformational change may be the signal responsible for coupling ATP hydrolysis to drug transport by inducing conformational changes in the transmembrane segments.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

The bromodomain: a chromatin browser?

Reversible modification of histone tails is a regulatory step in chromatin remodeling. The N-terminal tails of histones are signaling platforms that carry amino acid residues for post-translational modification and contribute to chromosomal higher order structure. These modifications are performed by a number of chromatin modulators such as histone (h) acetyltransferase, h-deacetylase, h-methyltransferase and h-kinase. Large numbers of these enzymes as well as other chromatin-associated proteins share the bromodomain, a signature protein motif. Structural studies reveal not only wide structural conservation of bromodomains but also envision a possible role of this domain in the recognition of specific modified residues in the histone tails. The widespread presence of bromodomains in leukemogenic and cancer genes has provided a fundamental tool for studies of the role of epigenetic and chromatin remodeling in malignant diseases.

Acetyltransferases↗
PubMed2001

A functional genomic analysis of type 3 Streptococcus pneumoniae virulence.

Streptococcus pneumoniae remains a serious cause of morbidity and mortality in humans, but relatively little is known about the molecular basis of its pathogenesis. We used signature-tagged mutagenesis together with an analysis of S. pneumoniae genome sequence to identify and characterize genes required for pathogenesis. A library of signature-tagged mutants was created by insertion-duplication mutagenesis, and 1786 strains were analysed for their inability to survive and replicate in murine models of pneumonia and bacteraemia. One hundred and eighty-six mutant strains were identified as attenuated, and 56 were selected for further genetic characterization based on their ability to excise the integrated plasmid spontaneously. The genomic DNA inserts of the plasmids were cloned in Escherichia coli and sequenced. These sequences were subjected to database searches, including the S. pneumoniae genome sequence, which allowed us to examine the chromosomal regions flanking these genes. Most of the insertions were in probable operons, but no pathogenicity islands were found. Forty-two novel virulence loci were identified. Five strains mutated in genes involved in gene regulation, cation transport or stress tolerance were shown to be highly attenuated when tested individually in a murine respiratory tract infection model. Additional experiments also suggest that induction of competence for genetic transformation has a role in virulence.

Amino Acid Sequence↗
PubMed2001

Genomic expression responses to DNA-damaging agents and the regulatory role of the yeast ATR homolog Mec1p.

Eukaryotic cells respond to DNA damage by arresting the cell cycle and modulating gene expression to ensure efficient DNA repair. The human ATR kinase and its homolog in yeast, MEC1, play central roles in transducing the damage signal. To characterize the role of the Mec1 pathway in modulating the cellular response to DNA damage, we used DNA microarrays to observe genomic expression in Saccharomyces cerevisiae responding to two different DNA-damaging agents. We compared the genome-wide expression patterns of wild-type cells and mutants defective in Mec1 signaling, including mec1, dun1, and crt1 mutants, under normal growth conditions and in response to the methylating-agent methylmethane sulfonate (MMS) and ionizing radiation. Here, we present a comparative analysis of wild-type and mutant cells responding to these DNA-damaging agents, and identify specific features of the gene expression responses that are dependent on the Mec1 pathway. Among the hundreds of genes whose expression was affected by Mec1p, one set of genes appears to represent an MEC1-dependent expression signature of DNA damage. Other aspects of the genomic responses were independent of Mec1p, and likely independent of DNA damage, suggesting the pleiotropic effects of MMS and ionizing radiation. The complete data set as well as supplemental materials is available at http://www-genome.stanford.edu/mec1.

Cell Cycle Proteins↗
PubMed2025

Mutant p53 disrupts antioxidant defense in fallopian tube epithelium via GSTAs suppression: A pathway to serous tubal carcinogenesis.

High grade serous ovarian cancer (HGSOC) is the most common and aggressive type of epithelial ovarian cancer. The fimbria of the fallopian tube is the likely site of origin based on the presence of distinct precancerous lesions with TP53 signatures known clinically as serous tubal intraepithelial carcinoma (STICs) detected in this region in individuals at genetically high risk or with HGSOC. Previously we identified that matched fallopian tube epithelia (FTE) from fimbria and ampulla of normal fallopian tubes from premenopausal women exhibit differential expression of genes associated with antioxidant and inflammatory pathways. One gene, glutathione S-transferase 2 (GSTA2), showed both higher expression in the fimbria and in the follicular phase (pre-ovulation) compared to the ampulla, suggesting that GSTA2 expression may regulate reactive oxygen homeostasis in these cells in response to ovulation-related stress. Here, to understand how preneoplastic genomic alterations influence regulation of oxidative stress, FTE cells were isolated from healthy tissue and introduced with p53 mutations, from which expression and function of GSTA2 and other antioxidant enzymes were investigated. Mutant p53 downregulated the expression of GSTA2 and subsequently increased DNA damage. The combination of p53 mutation and dysregulated oxidative response likely promotes the genomic instability that initially drives the transformation to high grade serous ovarian carcinoma.

Female↗
PubMed2005

Deficiency in mitochondrial anionic phospholipid synthesis impairs cell wall biogenesis.

Cardiolipin (CL) is the signature lipid of the mitochondrial membrane and plays a key role in mitochondrial physiology and cell viability. The importance of CL is underscored by the finding that the severe genetic disorder Barth syndrome results from defective CL composition and acylation. Disruption of PGS1, which encodes the enzyme that catalyses the committed step of CL synthesis, results in loss of the mitochondrial anionic phospholipids phosphatidylglycerol and CL. The pgs1Delta mutant exhibits severe growth defects at 37 degrees C. To understand the essential functions of mitochondrial anionic lipids at elevated temperatures, we isolated suppressors of pgs1Delta that grew at 37 degrees C. The present review summarizes our analysis of suppression of pgs1Delta growth defects by a mutant that has a loss-of-function mutation in KRE5, a gene involved in cell wall biogenesis.

CDPdiacylglycerol-Serine O-Phosphatidyltransferase↗
PubMed1997

Mitochondrial D-loop diversity in Australian riverine and Australian desert Aborigines.

Population structure has been revealed in mitochondrial D-loop segment 1 (mt DLS1) sequences from Australian Aboriginal people in the Darling River region of NSW (Riverine) and from Yuendumu in central Australia (Desert). Comparison with five published global studies reveals that these Australians demonstrate greatest divergence from some Africans, least from Papua New Guinea (PNG) highlanders, and only slightly more divergence from some Pacific groups (Indonesian, Asian, Samoan, and coastal PNG). A median networks approach demonstrates that several hypervariable nucleotide sites within the DLS1 are likely to have undergone mutation independently. A comprehensive evaluation of specific nucleotide variants with the large amount of global sequence data now available has been achieved in three stages of analysis: (i) identification of key nucleotide variants (from the Cambridge reference sequence) in the Aboriginal Australian by pairwise comparison and construction of a 'local' median network, (ii) identification of key nucleotide variants in a selected global sample including Australian mtDLS1 types most different from each other, and (iii) calculation of the frequency with which these key nucleotide sites occur as variants in a greatly extended global sample. The third stage of the analysis revealed that nucleotides 16287 and 16356 are unique markers for representatives from the northern Riverine region. A 'thymine' at nucleotide 16223 is an informative signature of African and several identifiable non-African DLS1 types, whereas the 'cytosine' form is a marker for European, Pacific, and some Asian populations.

Humans↗
PubMed1996

Electron paramagnetic resonance (EPR) studies on hydrogenase-1 (HYD1) purified from a mutant strain (AP6) of Escherichia coli enhanced in HYD1.

Hydrogenase-1 (HYD1), overexpressed by twofold, has been purified to homogeneity and to a high specific activity from a mutant strain (AP6) of Escherichia coli which lacks hydrogenase-2. Plasma emission spectroscopy indicated that 0.93 atom of nickel and 11.4 iron atoms were present in HYD1. EPR studies on the as isolated HYD1 detected a complex 3Fe-4S signal and a Ni(III) species. Reduction with hydrogen gas caused disappearance of both the 3Fe-4S cluster and initial Ni(III) signals. At the same time the EPR signature (small g = 2.19 signal) of the activated hydrogenase appeared. The detection of a 4Fe-4S cluster signal was noted. Reduction of HYD1 with sodium dithionite caused all nickel signals to disappear. The 4Fe-4S complex intensity was slightly increased. The EPR responses in the three oxidation-reduction states are consistent with other known (NiFe)-hydrogenases.

Dithionite↗
PubMed2006

En block C-terminal charge cluster reversals in prestin (SLC26A5): effects on voltage-dependent electromechanical activity.

Prestin, the transmembrane motor protein is a novel protein underlying the motility of the outer hair cells. Nonlinear capacitance (NLC) or gating charge current, which can be observed in both auditory and transfected non-auditory cells, is the electrical signature of prestin's electromechanical activity. To test the functional role of the C-terminus of prestin, several charged residue clusters were reversed en-block by site-directed mutagenesis. They are D/E to K at 516, 518, 522, 524, 527, 528 and 531 (cluster a); R/K to D at 571, 572, 573, 576, 577 and 580 (cluster b); R to D at 571; and E/D to K at 608, 609, 610, 611, 612 and 613 (cluster c). These constructs were transfected into Chinese hamster ovary cells (CHO) and NLC recordings were performed to evaluate the effects of these charge substitutions. All of the mutants showed NLC. Charge cluster a reversal significantly reduced the maximum charge movement (Qmax). All but one mutation (charge cluster c reversal) shifted V(h), indicative of the operating voltage range, in the depolarizing direction. None of the mutations affected unitary charge movement (z). These data suggest that the C-terminus of prestin lies outside the membrane voltage field, and may play an important role in controlling the operating voltage range through control of the protein's conformational energy profile via allosteric means.

Amino Acid Sequence↗