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At least 595 records · Page 33Linked to original sources
PubMed2001

Dbest1, a Drosophila homolog of human Bestrophin, is not required for viability or photoreceptor integrity.

Best macular dystrophy (BMD) is an autosomal dominant human disease characterized by macular degeneration with juvenile onset (OMIM 153700). The disease is most often associated with mutations in Bestrophin, which encodes a novel protein with four putative transmembrane domains. However, complete loss-of-function mutations in Bestrophin have not been reported in humans or mice. We have identified three homologs of human Bestrophin in the Drosophila genome (dbest1-3). The protein products of these three genes share significant homology to a 364 amino acid N-terminal domain of human Bestrophin. We used P-element mutagenesis to delete dbest1, which encodes a protein with the highest amino acid similarity to Bestrophin. Three independent dbest1 mutants were recovered from the mutagenesis screen. Homozygous null mutations in dbest1 do not significantly alter the viability or fertility of mutant flies. Moreover, dbest1 mutants have normal photoreceptor morphology and function.

Amino Acid Sequence↗
PubMed2007

Three novel mutations in the activin receptor-like kinase 1 (ALK-1) gene in hereditary hemorrhagic telangiectasia type 2 in Brazilian patients.

Hereditary hemorrhagic telangiectasia (HHT) or Osler-Rendu-Weber disease is a systemic fibrovascular dysplasia with an autosomal dominant inheritance pattern. Mutations in two genes, endoglin and ALK-1, are known to cause HHT, both of which mediate signaling by transforming growth factor beta ligands in vascular endothelial cells. Ten patients were analyzed. Diagnosis of HHT was carried out by means of family history, recurrent bleeding, and the presence of multiple telangiectases lesions. Conformation-sensitive gel electrophoresis analyses with consistent abnormal migration patterns were cloned and sequenced using the MegaBace 1000 DNA automated analyzer. Three novel mutations were identified in the coding sequence of the ALK-1 gene in five patients and their families, which demonstrated clinical manifestations of HHT type 2. These mutations included a G insertion and a T deletion of single base pairs in exons 3 and 7, as well as missense mutations in exons 7 and 8 of the ALK-1 gene. These data indicate that loss-of-function mutations in a single allele of the ALK1 locus are sufficient to contribute to defects in maintaining endothelial integrity. We suggest the high rate of mutation detection and the small size of the ALK-1 gene make genomic sequencing a viable diagnostic test for HHT2.

Activin Receptors, Type II↗
PubMed1996

Extracellular proteins needed for C. elegans mechanosensation.

The mec-5 and mec-9 genes encode putative extracellular proteins that allow a set of six touch receptor neurons in C. elegans to respond to gentle touch. MEC-5 is a collagen made by the epidermal cells that surround the touch cells. Mutations causing touch insensitivity affect the Gly-X-Y repeats of this collagen. mec-9 produces two transcripts, the larger of which is expressed in the touch cells and two PVD neurons. This transcript encodes a protein with 5 Kunitz-type protease inhibitor domains, 6 EGF-like repeats (2 of the Ca(2+)-binding type), and a glutamic acid-rich region. Missense mutations causing touch insensitivity affect both the EGF-like and Kunitz domains. Since mec-9 loss of function mutations dominantly enhance the touch insensitive phenotype of several mec-5 mutations, MEC-5 and MEC-9 may interact. We propose that these proteins provide an extracellular attachment point for the mechanosensory channels of the touch cells.

Amino Acid Sequence↗
PubMed2005

tp53 mutant zebrafish develop malignant peripheral nerve sheath tumors.

TP53 is the most frequently mutated tumor suppressor gene in human cancer, with nearly 50% of all tumors exhibiting a loss-of-function mutation. To further elucidate the genetic pathways involving TP53 and cancer, we have exploited the zebrafish, a powerful vertebrate model system that is amenable to whole-genome forward-genetic analysis and synthetic-lethal screens. Zebrafish lines harboring missense mutations in the tp53 DNA-binding domain were identified by using a target-selected mutagenesis strategy. Homozygous mutant fish from two of these lines were viable and exhibited mutations similar to those found in human cancers (tp53(N168K) and tp53(M214K)). Although homozygous tp53(N168K) mutants were temperature-sensitive and suppressed radiation-induced apoptosis only at 37 degrees C, cells in the tp53(M214K) embryos failed to undergo apoptosis in response to gamma radiation at both 28 and 37 degrees C. Unlike wild-type control embryos, irradiated tp53(M214K) embryos also failed to up-regulate p21 and did not arrest at the G(1)/S checkpoint. Beginning at 8.5 months of age, 28% of tp53(M214K) mutant fish developed malignant peripheral nerve sheath tumors. In addition to providing a model for studying the molecular pathogenic pathways of malignant peripheral nerve sheath tumors, these mutant zebrafish lines provide a unique platform for modifier screens to identify genetic mutations or small molecules that affect tp53-related pathways, including apoptosis, cell-cycle delay, and tumor suppression.

Alleles↗
PubMed1999

Intracellular glycerol levels modulate the activity of Sln1p, a Saccharomyces cerevisiae two-component regulator.

The HOG mitogen-activated protein kinase pathway mediates the osmotic stress response in Saccharomyces cerevisiae, activating genes like GPD1 (glycerol phosphate dehydrogenase), required for survival under hyperosmotic conditions. Activity of this pathway is regulated by Sln1p, a homolog of the "two-component" histidine kinase family of signal transduction molecules prominent in bacteria. Sln1p also regulates the activity of a Hog1p-independent pathway whose transcriptional output can be monitored using an Mcm1p-dependent lacZ reporter gene. The relationship between the two Sln1p branches is unclear, however, the requirement for unphosphorylated pathway intermediates in Hog1p pathway activation and for phosphorylated intermediates in the activation of the Mcm1p reporter suggests that the two Sln1p branches are reciprocally regulated. To further investigate the signals and molecules involved in modulating Sln1p activity, we have screened for new mutations that elevate the activity of the Mcm1p-dependent lacZ reporter gene. We find that loss of function mutations in FPS1, a gene encoding the major glycerol transporter in yeast activates the reporter in a SLN1-dependent fashion. We propose that elevated intracellular glycerol levels in the fps1 mutant shift Sln1p to the phosphorylated state and trigger the Sln1-dependent activity of the Mcm1 reporter. These observations are consistent with a model in which Sln1p autophosphorylation is triggered by a hypo-osmotic stimulus and indicate that the Sln1p osmosensor is tied generally to osmotic balance, and may not specifically sense an external osmolyte.

Base Sequence↗
PubMed2006

Mining for allosteric information: natural mutations and positional sequence conservation in pyruvate kinase.

Although the amino acid sequences and the structures of pyruvate kinase (PYK) isozymes are highly conserved, allosteric regulations differ. This suggests that amino acids with low conservation play important roles in the allosteric mechanism. The current work exploits a 'natural screen'- the 122 point mutations identified in the human gene encoding the erythrocyte PYK isozyme and associated with nonspherocytic hemolytic anemia - to learn what amino acid positions in PYK may be important for allosteric regulations. In addition to the mutations, we consider the conservation of each amino acid position across 241 PYK sequences. Three groups of residue positions have been created, those with: (1) no disease causing mutation identified; (2) a disease causing mutation identified and high conservation across isozymes; and (3) a disease causing mutation identified and low conservation. Mutations at positions not identified in the natural screen are likely to be tolerated with minimal loss of function. Mutations at highly conserved positions are more likely to disrupt properties common to all PYK isozymes (e.g., structure, catalysis). Residues in the third group are likely to be involved in roles that are necessary for function but not common to all isozymes (e.g., allostery). Many of the Group 3 residues are located in the C-domain and to a lesser extent the A domain.

Allosteric Regulation↗
PubMed2004

Structure-based assessment of missense mutations in human BRCA1: implications for breast and ovarian cancer predisposition.

The BRCA1 gene from individuals at risk of breast and ovarian cancers can be screened for the presence of mutations. However, the cancer association of most alleles carrying missense mutations is unknown, thus creating significant problems for genetic counseling. To increase our ability to identify cancer-associated mutations in BRCA1, we set out to use the principles of protein three-dimensional structure as well as the correlation between the cancer-associated mutations and those that abolish transcriptional activation. Thirty-one of 37 missense mutations of known impact on the transcriptional activation function of BRCA1 are readily rationalized in structural terms. Loss-of-function mutations involve nonconservative changes in the core of the BRCA1 C-terminus (BRCT) fold or are localized in a groove that presumably forms a binding site involved in the transcriptional activation by BRCA1; mutations that do not abolish transcriptional activation are either conservative changes in the core or are on the surface outside of the putative binding site. Next, structure-based rules for predicting functional consequences of a given missense mutation were applied to 57 germ-line BRCA1 variants of unknown cancer association. Such a structure-based approach may be helpful in an integrated effort to identify mutations that predispose individuals to cancer.

BRCA1 Protein↗
PubMed2003

Echinoid mutants exhibit neurogenic phenotypes and show synergistic interactions with the Notch signaling pathway.

During neurogenesis in Drosophila, groups of ectodermal cells are endowed with the capacity to become neuronal precursors. The Notch signaling pathway is required to limit the neuronal potential to a single cell within each group. Loss of genes of the Notch signaling pathway results in a neurogenic phenotype: hyperplasia of the nervous system accompanied by a parallel loss of epidermis. Echinoid (Ed), a cell membrane associated Immunoglobulin C2-type protein, has previously been shown to be a negative regulator of the EGFR pathway during eye and wing vein development. Using in situ hybridization and antibody staining of whole-mount embryos, we show that Ed has a dynamic expression pattern during embryogenesis. Embryonic lethal alleles of ed reveal a role of Ed in restricting neurogenic potential during embryonic neurogenesis, and result in a phenotype similar to that of loss-of-function mutations of Notch signaling pathway genes. In this process Ed interacts closely with the Notch signaling pathway. Loss of ed suppresses the loss of neuronal elements caused by ectopic activation of the Notch signaling pathway. Using a temperature-sensitive allele of ed we show, furthermore, that Ed is required to suppress sensory bristles and for proper wing vein specification during adult development. In these processes also, ed acts in close concert with genes of the Notch signaling pathway. Thus the extra wing vein phenotype of ed is enhanced upon reduction of Delta (Dl) or Enhancer of split [E(spl)] proteins. Overexpression of the membrane-tethered extracellular region of Ed results in a dominant-negative phenotype. This phenotype is suppressed by overexpression of E(spl)m7 and enhanced by overexpression of Dl. Our work establishes a role of Ed during embryonic nervous system development, as well as adult sensory bristle specification and shows that Ed interacts synergistically with the Notch signaling pathway.

Animals↗
PubMed2001

Genetic analysis of the Drosophila Gs(alpha) gene.

One of the best understood signal transduction pathways activated by receptors containing seven transmembrane domains involves activation of heterotrimeric G-protein complexes containing Gs(alpha), the subsequent stimulation of adenylyl cyclase, production of cAMP, activation of protein kinase A (PKA), and the phosphorylation of substrates that control a wide variety of cellular responses. Here, we report the identification of "loss-of-function" mutations in the Drosophila Gs(alpha) gene (dgs). Seven mutants have been identified that are either complemented by transgenes representing the wild-type dgs gene or contain nucleotide sequence changes resulting in the production of altered Gs(alpha) protein. Examination of mutant alleles representing loss-of-Gs(alpha) function indicates that the phenotypes generated do not mimic those created by mutational elimination of PKA. These results are consistent with the conclusion reached in previous studies that activation of PKA, at least in these developmental contexts, does not depend on receptor-mediated increases in intracellular cAMP, in contrast to the predictions of models developed primarily on the basis of studies in cultured cells.

Adenylyl Cyclases↗
PubMed2000

Human T-cell leukemia virus type 1 Tax shuttles between functionally discrete subcellular targets.

Human T-cell leukemia virus type 1 (HTLV-1) Tax is a nuclear protein with striking pleiotropic functionality. We recently demonstrated that Tax localizes to a multicomponent nuclear speckled structure (Tax speckled structure [TSS]). Here, we examine these structures further and identify a partial overlap of TSS with transcription hot spots. We used a strategy of directed expression via fusion proteins to determine if these transcription sites are the subtargets within TSS required for Tax function. When fused to human immunodeficiency virus type 1 (HIV-1) Tat, the resulting Tat-Tax fusion protein displayed neither a Tat-like nor a Tax-like pattern but rather was targeted specifically to the transcription subsites. The Tat-Tax fusion was able to activate both the HIV-1 long terminal repeat (LTR) and the HTVL-1 LTR at the same level as the individual component; thus, targeting proteins to transcription hot spots was compatible with both Tax and Tat transcription function. In contrast, the fusion with HIV-1 Rev, Rev-Tax, resulted in a pattern of expression that was largely Rev-like (nucleolar and cytoplasmic). The reduced localization of Rev-Tax to transcription sites was reflected in a 10-fold drop in activation of the HTLV-1 LTR. However, there was no loss in the ability of Tax to activate via NF-kappaB. Thus, NF-kappaB-dependent Tax function does not require targeting of Tax to these transcription sites and suggests that activation via NF-kappaB is a cytoplasmic function. Selective mutation of the nuclear localization signal site in the Rev portion resulted in retargeting of Rev-Tax to TSS and subsequent restoration of transcription function, demonstrating that inappropriate localization preceded loss of function. Mutation of the nuclear export signal site in the Rev portion had no effect on transcription, although the relative amount of Rev-Tax in the cytoplasm was reduced. Finally, in explaining how Tax can occupy multiple subcellular sites, we show that Tax shuttles from the nucleus to the cytoplasm in a heterokaryon fusion assay. Thus, pleiotropic functionality by Tax is regulatable via shuttling between discrete subcellular compartments.

Blotting, Western↗
PubMed2001

Endocrine manifestations of stimulatory G protein alpha-subunit mutations and the role of genomic imprinting.

The heterotrimeric G protein G(s) couples hormone receptors (as well as other receptors) to the effector enzyme adenylyl cyclase and is therefore required for hormone-stimulated intracellular cAMP generation. Receptors activate G(s) by promoting exchange of GTP for GDP on the G(s) alpha-subunit (G(s)alpha) while an intrinsic GTPase activity of G(s)alpha that hydrolyzes bound GTP to GDP leads to deactivation. Mutations of specific G(s)alpha residues (Arg(201) or Gln(227)) that are critical for the GTPase reaction lead to constitutive activation of G(s)-coupled signaling pathways, and such somatic mutations are found in endocrine tumors, fibrous dysplasia of bone, and the McCune-Albright syndrome. Conversely, heterozygous loss-of-function mutations may lead to Albright hereditary osteodystrophy (AHO), a disease characterized by short stature, obesity, brachydactyly, sc ossifications, and mental deficits. Similar mutations are also associated with progressive osseous heteroplasia. Interestingly, paternal transmission of GNAS1 mutations leads to the AHO phenotype alone (pseudopseudohypoparathyroidism), while maternal transmission leads to AHO plus resistance to several hormones (e.g., PTH, TSH) that activate G(s) in their target tissues (pseudohypoparathyroidism type IA). Studies in G(s)alpha knockout mice demonstrate that G(s)alpha is imprinted in a tissue-specific manner, being expressed primarily from the maternal allele in some tissues (e.g., renal proximal tubule, the major site of renal PTH action), while being biallelically expressed in most other tissues. Disrupting mutations in the maternal allele lead to loss of G(s)alpha expression in proximal tubules and therefore loss of PTH action in the kidney, while mutations in the paternal allele have little effect on G(s)alpha expression or PTH action. G(s)alpha has recently been shown to be also imprinted in human pituitary glands. The G(s)alpha gene GNAS1 (as well as its murine ortholog Gnas) has at least four alternative promoters and first exons, leading to the production of alternative gene products including G(s)alpha, XLalphas (a novel G(s)alpha isoform that is expressed only from the paternal allele), and NESP55 (a chromogranin-like protein that is expressed only from the maternal allele). A fourth alternative promoter and first exon (exon 1A) located approximately 2.5 kb upstream of the G(s)alpha promoter is normally methylated on the maternal allele and transcriptionally active on the paternal allele. In patients with isolated renal resistance to PTH (pseudohypoparathyroidism type IB), the exon 1A promoter region has a paternal-specific imprinting pattern on both alleles (unmethylated, transcriptionally active), suggesting that this region is critical for the tissue-specific imprinting of G(s)alpha. The GNAS1 imprinting defect in pseudohypoparathyroidism type IB is predicted to decrease G(s)alpha expression in renal proximal tubules. Studies in G(s)alpha knockout mice also demonstrate that this gene is critical in the regulation of lipid and glucose metabolism.

Animals↗
PubMed1998

A loss-of-function mechanism of nigral neuron death without Lewy body formation: autosomal recessive juvenile parkinsonism (AR-JP).

We present a genetic model of selective nigral neuron death without Lewy body formation--autosomal recessive juvenile parkinsonism (AR-JP). Mapping of AR-JP gene to a single recessive locus on chromosome 6q25.2-27 is a strong indication of the idea that a loss-of-function mutation of a single gene is sufficient to cause selective nigral neuron death. The absence of Lewy body formation in AR-JP is important, because most cases of neuron death caused by loss-of-function mechanism are not accompanied by inclusion body. Our findings clearly indicate that nigral cells are critically dependent for their survival on the function of AR-JP protein. This raises an important question of whether or not AR-JP protein contributes to the downstream pathway of cell death in Parkinson's disease.

Cell Death↗
PubMed2006

Defective splicing of Megf7/Lrp4, a regulator of distal limb development, in autosomal recessive mulefoot disease.

Mulefoot disease (MFD) is an autosomal recessive disorder of phenotypically variable expression that causes syndactyly in certain strains of cows. MFD maps to a narrow interval on bovine chromosome 15 that is syntenic to human chromosome 11p12-p11.2. This region contains MEGF7/LRP4 (approved gene symbol LRP4), a gene that encodes a member of the multifunctional low-density lipoprotein receptor gene family. Targeted and naturally occurring mutations in the murine Megf7/Lrp4 gene, a putative coreceptor in the Wnt signaling pathway, cause polysyndactyly in the rodent. Thus, Megf7/Lrp4 is a strong candidate for the MFD mutation. Using PCR analysis of tissue samples and sperm from confirmed homozygous MFD carriers, we have identified a functional single base pair mutation in the affected animals. We show that a G --> A transition at the first nucleotide in the splice donor site of intron 37 completely disables this splice site. The abnormal splicing that is caused by this mutation predicts the generation of a dysfunctional membrane-anchored receptor lacking the normal cytoplasmic domain. These findings confirm that autosomal recessive loss-of-function mutations in Megf7/Lrp4 result in phenotypically similar forms of syndactyly in different mammalian species and that such mutations are the cause of MFD in bovines.

Amino Acid Sequence↗
PubMed1993

Genetic and molecular characterization of a Notch mutation in its Delta- and Serrate-binding domain in Drosophila.

The Drosophila Notch gene product is a transmembrane protein that functions as a receptor of intercellular signals in several Drosophila developmental processes. Two other transmembrane proteins, encoded by the genes Delta and Serrate, genetically and molecularly behave as Notch ligands. All these proteins share the presence of epidermal growth factor (EGF)-like repeats in their extracellular domain. The Notch protein has 36 EGF-like repeats, 2 of which, numbers 11 and 12, are required for the interaction with the Delta and Serrate ligands. We have isolated and molecularly characterized a Notch mutation in its Delta- and Serrate-binding domain that behaves genetically as both a Notch antimorphic and a loss-of-function mutation. This mutation, NM1, carries a Glu-->Val substitution in the Notch EGF repeat 12. The NM1 allele interacts with other Notch alleles such as Abruptex and split and with mutations in the Notch-ligand genes Delta and Serrate. The basis for the genetic antimorphism of NM1 seems to reside in the titration of Notch wild-type products into NM1/N+ nonfunctional dimers and/or the titration of Delta products into nonfunctional ligand-receptor complexes.

Animals↗
PubMedDate not supplied

RET tyrosine kinase signaling in development and cancer.

The variety of diseases caused by mutations in RET receptor tyrosine kinase provides a classic example of phenotypic heterogeneity. Gain-of-function mutations of RET are associated with human cancer. Gene rearrangements juxtaposing the tyrosine kinase domain to heterologous gene partners have been found in sporadic papillary carcinomas of the thyroid (PTC). These rearrangements generate chimeric RET/PTC oncogenes. In the germline, point mutations of RET are responsible for multiple endocrine neoplasia type 2 (MEN 2A and 2B) and familial medullary thyroid carcinoma (FMTC). Both MEN 2 mutations and PTC gene rearrangements potentiate the intrinsic tyrosine kinase activity of RET and, ultimately, activate the RET downstream targets. Loss-of-function mutations of RET cause Hirschsprung's disease (HSCR) or colonic aganglionosis. A deeper understanding of the molecular signaling of normal versus abnormal RET activity in cancer will enable the development of potential new treatments for patients with sporadic and inherited thyroid cancer or MEN 2 syndrome. We now review the role and mechanisms of RET signaling in development and carcinogenesis.

Hirschsprung Disease↗
PubMed2002

High bone density due to a mutation in LDL-receptor-related protein 5.

BACKGROUND: Osteoporosis is a major public health problem of largely unknown cause. Loss-of-function mutations in the gene for low-density lipoprotein receptor-related protein 5 (LRP5), which acts in the Wnt signaling pathway, have been shown to cause osteoporosis-pseudoglioma. METHODS: We performed genetic and biochemical analyses of a kindred with an autosomal dominant syndrome characterized by high bone density, a wide and deep mandible, and torus palatinus. RESULTS: Genetic analysis revealed linkage of the syndrome to chromosome 11q12-13 (odds of linkage, >1 million to 1), an interval that contains LRP5. Affected members of the kindred had a mutation in this gene, with valine substituted for glycine at codon 171 (LRP5V171). This mutation segregated with the trait in the family and was absent in control subjects. The normal glycine lies in a so-called propeller motif that is highly conserved from fruit flies to humans. Markers of bone resorption were normal in the affected subjects, whereas markers of bone formation such as osteocalcin were markedly elevated. Levels of fibronectin, a known target of signaling by Wnt, a developmental protein, were also elevated. In vitro studies showed that the normal inhibition of Wnt signaling by another protein, Dickkopf-1 (Dkk-1), was defective in the presence of LRP5V171 and that this resulted in increased signaling due to unopposed Wnt activity. CONCLUSIONS: The LRP5V171 mutation causes high bone density, with a thickened mandible and torus palatinus, by impairing the action of a normal antagonist of the Wnt pathway and thus increasing Wnt signaling. These findings demonstrate the role of altered LRP5 function in high bone mass and point to Dkk as a potential target for the prevention or treatment of osteoporosis.

Biomarkers↗
PubMed1999

Analysis of alkaptonuria (AKU) mutations and polymorphisms reveals that the CCC sequence motif is a mutational hot spot in the homogentisate 1,2 dioxygenase gene (HGO).

We recently showed that alkaptonuria (AKU) is caused by loss-of-function mutations in the homogentisate 1,2 dioxygenase gene (HGO). Herein we describe haplotype and mutational analyses of HGO in seven new AKU pedigrees. These analyses identified two novel single-nucleotide polymorphisms (INV4+31A-->G and INV11+18A-->G) and six novel AKU mutations (INV1-1G-->A, W60G, Y62C, A122D, P230T, and D291E), which further illustrates the remarkable allelic heterogeneity found in AKU. Reexamination of all 29 mutations and polymorphisms thus far described in HGO shows that these nucleotide changes are not randomly distributed; the CCC sequence motif and its inverted complement, GGG, are preferentially mutated. These analyses also demonstrated that the nucleotide substitutions in HGO do not involve CpG dinucleotides, which illustrates important differences between HGO and other genes for the occurrence of mutation at specific short-sequence motifs. Because the CCC sequence motifs comprise a significant proportion (34.5%) of all mutated bases that have been observed in HGO, we conclude that the CCC triplet is a mutational hot spot in HGO.

Alkaptonuria↗
PubMed2002

Molecular mechanism of a COOH-terminal gating determinant in the ROMK channel revealed by a Bartter's disease mutation.

The ROMK subtypes of inward-rectifier K(+) channels mediate potassium secretion and regulate NaCl reabsorption in the kidney. Loss-of-function mutations in this pH-sensitive K(+) channel cause Bartter's disease, a familial salt wasting nephropathy. One disease-causing mutation truncates the extreme COOH-terminus and induces a closed gating conformation. Here we identify a region within the deleted domain that plays an important role in pH-dependent gating. The domain contains a structural element that functionally interacts with the pH sensor in the cytoplasmic NH(2)-terminus to set a physiological range of pH sensitivity. Removal of the domain shifts the pK(a) towards alkaline pH values, causing channel inactivation under physiological conditions. Suppressor mutations within the pH sensor rescued channel gating and trans addition of the cognate peptide restored pH sensitivity. A specific interdomain interaction was revealed in an in vitro protein-protein binding assay between the NH(2)- and COOH-terminal cytoplasmic domains expressed as bacterial fusion proteins. These results provide new insights into the molecular mechanisms underlying Kir channel regulation and channel gating defects that are associated with Bartter's disease.

Amino Acid Sequence↗