Slow Gating of Gap Junction Channels and Calmodulin

Peracchia, Camillo; Wang, X.G.; Peracchia, Lillian L.

doi:10.1007/s002320010015

Cited by 120 publications

(240 citation statements)

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“…Cx43 has been shown to interact with CaM, and a specific binding site was recently [12] localised to the cytoplasmic loop, between residues 136-158. Similar sites have been characterized or suggested to be present in other connexins [13][14][15][16][17], indicating a putative general mechanism of gap junction regulation by CaM. Currently, no highresolution data on the CaM-cx43 complex exist, and the sequence homology between cx43 and structurally characterized CaM target proteins is low.…”

Section: Introductionmentioning

confidence: 83%

Complex formation between calmodulin and a peptide from the intracellular loop of the gap junction protein connexin43: Molecular conformation and energetics of binding

Myllykoski

Kuczera

Kursula

2009

Biophysical Chemistry

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. Complex formation between calmodulin and a peptide from the intracellular loop of the gap junction protein connexin43: Molecular conformation and energetics of binding. Biophysical Chemistry, Elsevier, 2009, 144 (3) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractGap junctions are formed by a family of transmembrane proteins, connexins.Connexin43 is a widely studied member of the family, being ubiquitously expressed in a variety of tissues and a target of a large number of disease mutations. The intracellular loop of connexin43 has been shown to include a calmodulin binding domain, but detailed 3-dimensional data on the structure of the complex are not available. In this study, we used a synthetic peptide from this domain to reveal the conformation of the calmodulin-peptide complex by small angle X-ray scattering.Upon peptide binding, calmodulin lost its dumbbell shape, adopting a more globular conformation. We also studied the energetics of the interaction using calorimetry and computational methods. All our data indicate that calmodulin binds to the peptide from cx43 in the classical 'collapsed' conformation.

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Section: Introductionmentioning

confidence: 83%

Complex formation between calmodulin and a peptide from the intracellular loop of the gap junction protein connexin43: Molecular conformation and energetics of binding

Myllykoski

Kuczera

Kursula

2009

Biophysical Chemistry

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“…During the last decade, significant progress has been made toward understanding the molecular mechanisms of pH-dependent modulation of GJs and hemichannels (2,(9)(10)(11)(12). Several domains in the cytoplasmic loop and C terminus of connexin43 (Cx43) appear to be involved in pH-dependent gating (2,9,11,12).…”

mentioning

confidence: 99%

“…Several domains in the cytoplasmic loop and C terminus of connexin43 (Cx43) appear to be involved in pH-dependent gating (2,9,11,12). Furthermore, pH-dependent interaction of connexins with other cytoplasmic proteins may be important in the remodeling of connexins and in protection from lesion spread after local ischemic injury (13,14).…”

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confidence: 99%

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pH-dependent modulation of voltage gating in connexin45 homotypic and connexin45/connexin43 heterotypic gap junctions

Palacios-Prado

Briggs

Skeberdis

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Intracellular pH (pH i ) can change during physiological and pathological conditions causing significant changes of electrical and metabolic cell-cell communication through gap junction (GJ) channels. In HeLa cells expressing wild-type connexin45 (Cx45) as well as Cx45 and Cx43 tagged with EGFP, we examined how pH i affects junctional conductance (g j ) and g j dependence on transjunctional voltage (V j ). To characterize V j gating, we fit the g j -V j relation using a stochastic four-state model containing one V j -sensitive gate in each apposed hemichannel (aHC); aHC open probability was a Boltzmann function of the fraction of V j across it. Using the model, we estimated gating parameters characterizing sensitivity to V j and number of functional channels. In homotypic Cx45 and heterotypic Cx45/Cx43-EGFP GJs, pH i changes from 7.2 to ∼8.0 shifted g j -V j dependence of Cx45 aHCs along the V j axis resulting in increased probability of GJ channels being in the fully open state without change in the slope of g j dependence on V j . In contrast, acidification shifted g j -V j dependence in the opposite direction, reducing open probability; acidification also reduced the number of functional channels. Correlation between the number of channels in Cx45-EGFP GJs and maximal g j achieved under alkaline conditions showed that only ∼4% of channels were functional. The acid dissociation constant (pK a ) of g j -pH i dependence of Cx45/Cx45 GJs was ∼7. The pK a of heterotypic Cx45/Cx43-EGFP GJs was lower, ∼6.7, between the pK a s of Cx45 and Cx43-EGFP (∼6.5) homotypic GJs. In summary, pH i significantly modulates junctional conductance of Cx45 by affecting both V j gating and number of functional channels.cell-cell coupling | pH-dependent gating | EGFP | hemichannel | connexon C hanges in intracellular pH (pH i ) take place under different physiological and pathological conditions, and H + ions have a broad effect on cell function including cell-cell electrical and metabolic communication mediated by gap junctions (GJs) and paracrine signaling through nonjunctional/unapposed hemichannels (1-4). Modest pH i changes have been observed under normal physiological conditions [e.g., changes of neuronal activity or the resting potential (5, 6)], and greater changes occur under pathological conditions such as hypoxia, ischemia, or epilepsy (4,7,8).During the last decade, significant progress has been made toward understanding the molecular mechanisms of pH-dependent modulation of GJs and hemichannels (2, 9-12). Several domains in the cytoplasmic loop and C terminus of connexin43 (Cx43) appear to be involved in pH-dependent gating (2, 9, 11, 12). Furthermore, pH-dependent interaction of connexins with other cytoplasmic proteins may be important in the remodeling of connexins and in protection from lesion spread after local ischemic injury (13,14).GJs provide channels with an inner diameter of ∼1.4 nm between the interiors of the coupled cells. This link allows the spread of electrical potential and small metabolites. Each GJ cha...

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“…Diferentes mecanismos atuam na regulação desses estados definindo a permeabilidade das JCs. Os fatores regulatórios podem ser determinados por alterações da concentração de hidrogênio (pH), concentração de cálcio intra/extracelular, interações com moléculas, ou até mesmo a diferença de voltagem existente entre as células acopladas (Burt, 1987, Bukauskas, Verselis, 2004, Peracchia, 2004.…”

Section: Jcs E Conexinasunclassified

Caracterização de conexinas neuronais no desenvolvimento pós-natal do hipocampo de ratos.

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Slow Gating of Gap Junction Channels and Calmodulin

Cited by 120 publications

References 34 publications

Complex formation between calmodulin and a peptide from the intracellular loop of the gap junction protein connexin43: Molecular conformation and energetics of binding

Complex formation between calmodulin and a peptide from the intracellular loop of the gap junction protein connexin43: Molecular conformation and energetics of binding

pH-dependent modulation of voltage gating in connexin45 homotypic and connexin45/connexin43 heterotypic gap junctions

Caracterização de conexinas neuronais no desenvolvimento pós-natal do hipocampo de ratos.

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