Calmodulin Directly Gates Gap Junction Channels

Peracchia, Camillo; Sotkis, A. V.; Wang, Xiao G.; Peracchia, Lillian L.; Persechini, Anthony

doi:10.1074/jbc.m004007200

Cited by 103 publications

(110 citation statements)

References 40 publications

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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: 82%

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: 82%

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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“…The occurrence of gap junctions between adjoining chemosensitive neurons suggests that either electrical coupling or metabolic coupling may be involved in central chemoreception of CO 2 and H ϩ and cardiorespiratory control. As pointed out elsewhere (18), this hypothesis is intriguing because intracellular acidification, which has been proposed as the proximate stimulus for the central chemoreceptors (44), is also reported to uncouple gap junctions in many types of networks, either directly via increased [H ϩ ] (56) or indirectly via a pH i -dependent process (43). This raises the question, How sensitive is G j in chemosensitive neurons to CO 2 -induced intracellular acidification?…”

Section: Central Co2/h ؉ Chemoreceptionmentioning

confidence: 99%

Role of gap junctions in CO₂ chemoreception and respiratory control

Dean

Ballantyne

Cardone

et al. 2002

American Journal of Physiology-Lung Cellular and Molecular Phys

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Gap junctions are composed of connexins, which are organized into intercellular channels that form transmembrane pathways between neurons (cell-cell coupling), and in some cases, neurons and glia, for exchange of ions and small molecules (metabolic coupling) and ionic current (electrical coupling). Cell-cell coupling via gap junctions has been identified in brain stem neurons that function in CO2/H+ chemoreception and respiratory rhythmogenesis; however, the exact roles of gap junctions in respiratory control are undetermined. Here we review the methods commonly used to study gap junctions in the mammalian brain stem under in vitro and in vivo conditions and briefly summarize the anatomical, pharmacological, and electrophysiological evidence to date supporting roles for cell-cell coupling in respiratory rhythmogenesis and central chemoreception. Specific research questions related to the role of gap junctions in respiratory control are suggested for future research.

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“…In targeted immunoprecipitation experiments with likely partners, Cx32 has previously been shown to interact with Caveolin1 (7), Cx26 (8), occludin (9), and calmodulin (10). To identify additional binding partners, using an unbiased , incubated with lysates from murine liver, and then probed with HRP-tagged anti-Cx32 antibodies (Sigma).…”

Section: Resultsmentioning

confidence: 99%

The Gap Junction Protein Connexin32 Interacts with the Src Homology 3/Hook Domain of Discs Large Homolog 1

Duffy

Iacobas

Hotchkiss

et al. 2007

Journal of Biological Chemistry

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Scaffolding of membrane proteins is a common strategy for forming complexes of proteins, including some connexins, within membrane microdomains. Here we describe studies indicating that Cx32 interacts with a PDZ-containing scaffolding protein, Dlgh1 (Discs Large homolog 1). Initial screens of liver lysates using antibody arrays indicated an interaction between Cx32 and Dlgh1 that was confirmed using coimmunoprecipitation studies. Yeast two-hybrid complementation determined that the Cx32 bound via interaction with the SH3/Hook domain of Dlgh1. Confocal microscopy of liver sections revealed that Cx32 and Dlgh1 could colocalize in hepatocyte membranes in wild type mice. Examination of levels and localization of Dlgh1 in livers from Cx32 null mice indicate that, in the absence of Cx32, Dlgh1 was decreased, and the remainder was translocated from the hepatocyte membrane to the nucleus with some remaining in cytoplasmic compartments. This translocation was confirmed by Western blots comparing Dlgh1 levels in nuclear extracts from wild type and Cx32 null murine livers. Using SKHep cells stably transfected with Cx32 under the control of a tet-off promoter, we found that acute removal of Cx32 led to a decrease of membrane-localized Dlgh1 and an increase in the nuclear localization of this tumor suppressor protein. Together, these results suggest that loss of Cx32 alters the levels, localization, and interactions of the tumor suppressor protein Dlgh1, events known in other systems to alter cell cycle and increase tumorigenicity.Connexins, of which there are more than 20 isoforms in mice and humans, are tetraspan proteins that oligomerize to form hexameric connexons. Connexons contributed by each cell interact head-to-head across the extracellular space, forming channels providing direct cytoplasmic continuity between cells.Aggregates of these channels, gap junctions, are found in almost all tissues. Connexins have intracellular amino-terminal cytoplasmic loops and carboxyl-terminal domains. Although much of the connexin sequence is highly conserved throughout the protein family, the amino acid sequences of intracellularly localized cytoplasmic loop and carboxyl-terminal domains vary markedly between connexin isoforms, and these regions likely confer isoform specificity. Carboxyl-terminal connexin domains, in particular, contain multiple sites for protein-protein interactions. For example, the major gap junction protein of heart and astrocytes, Connexin43 (Cx43), 2 possesses binding sites for Src homology 3 (SH3), SH2, WW, MAPK (mitogenactivated protein kinase), and PDZ within its carboxyl-terminal domain, and other connexins, although less well mapped, also display potential binding sites. The function of these proteinprotein interactions is not well understood, but many of them regulate the function of the gap junction channel (1). Interestingly, analysis of the primary sequence of the ␣ subdivision of connexins (which includes Cx43) for consensus binding sites indicates that many of these connexins have potential PDZ in...

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Calmodulin Directly Gates Gap Junction Channels

Abstract: Cytosolic changes control gap junction channel gating via poorly understood mechanisms. In the past two decades calmodulin participation in gating has been suggested, but compelling evidence for it has been lacking.

Cited by 103 publications

References 40 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

Role of gap junctions in CO₂ chemoreception and respiratory control

The Gap Junction Protein Connexin32 Interacts with the Src Homology 3/Hook Domain of Discs Large Homolog 1

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Calmodulin Directly Gates Gap Junction Channels

Abstract: Cytosolic changes control gap junction channel gating via poorly understood mechanisms. In the past two decades calmodulin participation in gating has been suggested, but compelling evidence for it has been lacking.

Cited by 103 publications

References 40 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

Role of gap junctions in CO2 chemoreception and respiratory control

The Gap Junction Protein Connexin32 Interacts with the Src Homology 3/Hook Domain of Discs Large Homolog 1

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Role of gap junctions in CO₂ chemoreception and respiratory control