Purification, Primary Structure, and Immunological Characterization of the 26-kDa Calsequestrin Binding Protein (Junctin) from Cardiac Junctional Sarcoplasmic Reticulum

Jones, Larry R.; Zhang, Lin; Sanborn, Kristi; Jorgensen, A O; Kelley, Jeff

doi:10.1074/jbc.270.51.30787

Cited by 205 publications

(263 citation statements)

References 59 publications

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“…48. Immunological detection was performed using polyclonal antibodies against AP-2aA (1 : 500; Santa Cruz, CA, USA) and CSQ 49 (1 : 2000; kindly provided by Dr. LR Jones, Indianapolis, USA). CSQ, a sarcoplasmic Ca 2 þ -storage protein, was reported to be unchanged in human heart failure 50 and was therefore used for standardization.…”

Section: Protein Analysismentioning

confidence: 99%

Transcription factor AP-2α triggers apoptosis in cardiac myocytes

et al. 2004

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Idiopathic-dilated cardiomyopathy (IDC) is a common primary myocardial disease of unknown etiology associated with apoptosis, cardiac dilatation, progressive heart failure and increased mortality. An elevation of the transcription factor activator protein 2a (AP-2a) is involved in vertebrate embryonic development and oncogenesis. Here, we show that AP-2a protein is expressed in the human heart and increased in human failing myocardium with IDC. Adenovirusmediated overexpression of human AP-2a triggered apoptosis and increased mRNA levels of Bcl-2 family members Bax and Bcl-x in rat cardiomyocytes. Immunohistological analysis of human myocardium revealed an increased percentage of AP-2a-positive nuclei in IDC and, interestingly, a colocalization of AP-2a-positive but not -negative cells with a caspasecleaved fragment of poly(ADP-ribose)polymerase. We suggest AP-2a as a novel cardiac regulator implicated in the activation of apoptosis in IDC.

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Section: Protein Analysismentioning

confidence: 99%

Transcription factor AP-2α triggers apoptosis in cardiac myocytes

et al. 2004

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“…Junctin (JCN), a 210-amino acid protein, is a sarcoplasmic reticulum (SR) integral component [1]. This 26-kDa protein contains a cytoplasmic NH2-terminal segment (residues 1-22), a single transmembrane segment (residues 23-44), and a SR intralumenal COOH-terminal segment (residues 45-210), which contains repeated KEKE motifs that are important for protein-protein interaction [1].…”

Section: Introductionmentioning

confidence: 99%

“…This 26-kDa protein contains a cytoplasmic NH2-terminal segment (residues 1-22), a single transmembrane segment (residues 23-44), and a SR intralumenal COOH-terminal segment (residues 45-210), which contains repeated KEKE motifs that are important for protein-protein interaction [1]. Indeed, in cardiac muscle, junctin forms a quaternary protein complex with the ryanodine receptor (RyR), calsequestrin(CSQ), and triadin in the SR lumen [2].…”

Section: Introductionmentioning

confidence: 99%

Junctin is a prominent regulator of contractility in cardiomyocytes

Fan

Yuan

Zhao

et al. 2007

Biochemical and Biophysical Research Communications

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Junctin is one of the components of the ryanodine receptor Ca release channel complex in sarcoplasmic reticulum. To determine the role of acute alteration of junctin protein levels on cardiomyocyte contractility, we used adenoviral-mediated gene transfer techniques in adult rat cardiomyocytes. Acute downregulation of junctin by 40% resulted in significant increases in cell shortening, rate of contraction (+dL/dt) and rate of relaxation (-dL/dt). The alteration of contractile parameters was associated with increased Ca transient peak and accelerated Ca decay. However, all these contractile and Ca kinetic parameters were depressed significantly when junctin levels were upregulated by 60%. Importantly, there were no alterations in other Ca cycling protein levels when junctin levels were either decreased or increased. These findings suggest that junctin plays a prominent role in cardiomyocyte Ca-cycling and contractility.

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“…Biochemical data indicate that in addition to RyRs, the JFM contains several protein constituents, including triadin, calsequestrin, junctin, histidine rich Ca 2þ binding protein (HRC), mitsugumin-29, junctophilin, 90 kDa protein or JP-45 (MacLennan and Wong, 1971;Hofmann et al, 1989;Caswell et al, 1991;Jones et al, 1995;Takeshima et al, 1998Takeshima et al, , 2000Froemming et al, 1999;Zorzato et al, 2000;Anderson et al, 2003). However, the JFM is also endowed with numerous other less abundant proteins having a molecular mass ranging between 20 and 120 kDa (Costello et al, 1986), whose identity and functional role are still obscure.…”

mentioning

confidence: 99%

“…Junctate is a 33 kDa protein which is expressed in a variety of tissues including brain, kidney, liver and heart and to a lesser extent in skeletal muscle; it results from alternative splicing of the same gene which generates junctin and aspartyl-b-hydroxylase (Dinchuk et al, 2000;Treves et al, 2000;Hong et al, 2001). Junctin is an integral SR membrane protein that forms a quaternary complex with the RyRs, calsequestrin, and triadin and has been shown to participate in Ca 2þ release from heart and skeletal muscle (Jones et al, 1995;Zhang et al, 1997). Different isoforms of aspartyl-b-hydroxylase can be generated by alternative splicing of the COOH-terminal tail however the full length isoform has enzymatic activity and catalyses the addition of hydroxyl groups to particular Asp or Asn residues within cEGF domains of numerous proteins (Gronke et al, 1990;Wang et al, 1991).…”

mentioning

confidence: 99%

Increased Ca²⁺ storage capacity of the skeletal muscle sarcoplasmic reticulum of transgenic mice over‐expressing membrane bound calcium binding protein junctate

Divet

Paesante

Grasso

et al. 2007

Journal Cellular Physiology

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Junctate is an integral sarco(endo)plasmic reticulum protein expressed in many tissues including heart and skeletal muscle. Because of its localization and biochemical characteristics, junctate is deemed to participate in the regulation of the intracellular Ca 2þ concentration. However, its physiological function in muscle cells has not been investigated yet. In this study we examined the effects of junctate over-expression by generating a transgenic mouse model which over-expresses junctate in skeletal muscle. Our results demonstrate that junctate over-expression induced a significant increase in SR Ca 2þ storage capacity which was paralleled by an increased 4-chloro-mcresol and caffeine-induced Ca 2þ release, whereas it did not affect SR Ca 2þ -dependent ATPase activity and SR Ca 2þ loading rates. In addition, junctate over-expression did not affect the expression levels of SR Ca 2þ binding proteins such as calsequestrin, calreticulin and sarcalumenin. These findings suggest that junctate over-expression is associated with an increase in the SR Ca 2þ storage capacity and releasable Ca 2þ content and support a physiological role for junctate in intracellular Ca 2þ homeostasis.

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Purification, Primary Structure, and Immunological Characterization of the 26-kDa Calsequestrin Binding Protein (Junctin) from Cardiac Junctional Sarcoplasmic Reticulum

Cited by 205 publications

References 59 publications

Transcription factor AP-2α triggers apoptosis in cardiac myocytes

Transcription factor AP-2α triggers apoptosis in cardiac myocytes

Junctin is a prominent regulator of contractility in cardiomyocytes

Increased Ca²⁺ storage capacity of the skeletal muscle sarcoplasmic reticulum of transgenic mice over‐expressing membrane bound calcium binding protein junctate

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Purification, Primary Structure, and Immunological Characterization of the 26-kDa Calsequestrin Binding Protein (Junctin) from Cardiac Junctional Sarcoplasmic Reticulum

Cited by 205 publications

References 59 publications

Transcription factor AP-2α triggers apoptosis in cardiac myocytes

Transcription factor AP-2α triggers apoptosis in cardiac myocytes

Junctin is a prominent regulator of contractility in cardiomyocytes

Increased Ca2+ storage capacity of the skeletal muscle sarcoplasmic reticulum of transgenic mice over‐expressing membrane bound calcium binding protein junctate

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Increased Ca²⁺ storage capacity of the skeletal muscle sarcoplasmic reticulum of transgenic mice over‐expressing membrane bound calcium binding protein junctate