Has the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin. PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides.
Interacting selectively and non-covalently with a cyclic nucleotide, a nucleotide in which the phosphate group is in diester linkage to two positions on the sugar residue.
J. Biol. Chem. 270, 26511-26522 (1995)[PubMed:7592869]
FK506, an immunosuppressant that prolongs allograft survival, is a co-drug with its intracellular receptor, FKBP12. The FKBP12.FK506 complex inhibits calcineurin, a critical signaling molecule during T-cell activation. FKBP12 was, until recently, the sole FKBP known to mediate calcineurin inhibition at clinically relevant FK506 concentrations. The best characterized cellular function of FKBP12 is the modulation of ryanodine receptor isoform-1, a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. Recently, a novel protein, FKBP12.6, was found to inhibit calcineurin at clinically relevant FK506 concentrations. We have cloned the cDNA encoding human FKBP12.6 and characterized the protein. In transfected Jurkat cells, FKBP12.6 is equivalent to FKBP12 at mediating the inhibitory effects of FK506. Upon binding rapamycin, FKBP12.6 complexes with the 288-kDa mammalian target of rapamycin. In contrast to FKBP12, FKBP12.6 is not associated with ryanodine receptor isoform-1 but with the distinct ryanodine receptor isoform-2 in cardiac muscle sarcoplasmic reticulum. Our results suggest that FKBP12.6 has both a unique physiological role in excitation-contraction coupling in cardiac muscle and the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin.
Interacting selectively and non-covalently with one or more specific sites on an ion channel, a protein complex that spans a membrane and forms a water-filled channel across the phospholipid bilayer allowing selective ion transport down its electrochemical gradient.
We isolated a novel gene encoding a protein highly homologous to human FK506-binding protein 12kDa (hFKBP-12) from a human fetal brain cDNA library and determined the full-length cDNA sequence. The cDNA clone contained the open reading frame of 324 nucleotides encoding 108 amino acid and revealed 76% identity in DNA sequence and 88% identity in predicted amino acid sequence with hFKBP-12. The DNA and amino-acid sequence of this gene, designated OTK4, also had homology with other FKBPs in species ranging from humans to prokaryotes. Recombinant protein, produced in E.coli transformed by a pGEX2T expression vector containing the OTK4 cDNA and purified, showed peptidyl-prolyl cis-trans isomerase activity like other FKBP proteins. An alternatively spliced form of the transcript found in the cDNA library contained a 45-bp insertion which included a stop codon. Although the biological function of the truncated version of OTK4 is unknown, both transcripts were ubiquitously expressed in human tissues examined by the reverse-transcriptase PCR (RT-PCR) method.
J. Biol. Chem. 270, 26511-26522 (1995)[PubMed:7592869]
FK506, an immunosuppressant that prolongs allograft survival, is a co-drug with its intracellular receptor, FKBP12. The FKBP12.FK506 complex inhibits calcineurin, a critical signaling molecule during T-cell activation. FKBP12 was, until recently, the sole FKBP known to mediate calcineurin inhibition at clinically relevant FK506 concentrations. The best characterized cellular function of FKBP12 is the modulation of ryanodine receptor isoform-1, a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. Recently, a novel protein, FKBP12.6, was found to inhibit calcineurin at clinically relevant FK506 concentrations. We have cloned the cDNA encoding human FKBP12.6 and characterized the protein. In transfected Jurkat cells, FKBP12.6 is equivalent to FKBP12 at mediating the inhibitory effects of FK506. Upon binding rapamycin, FKBP12.6 complexes with the 288-kDa mammalian target of rapamycin. In contrast to FKBP12, FKBP12.6 is not associated with ryanodine receptor isoform-1 but with the distinct ryanodine receptor isoform-2 in cardiac muscle sarcoplasmic reticulum. Our results suggest that FKBP12.6 has both a unique physiological role in excitation-contraction coupling in cardiac muscle and the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionBHF-UCL
J. Biol. Chem. 270, 26511-26522 (1995)[PubMed:7592869]
FK506, an immunosuppressant that prolongs allograft survival, is a co-drug with its intracellular receptor, FKBP12. The FKBP12.FK506 complex inhibits calcineurin, a critical signaling molecule during T-cell activation. FKBP12 was, until recently, the sole FKBP known to mediate calcineurin inhibition at clinically relevant FK506 concentrations. The best characterized cellular function of FKBP12 is the modulation of ryanodine receptor isoform-1, a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. Recently, a novel protein, FKBP12.6, was found to inhibit calcineurin at clinically relevant FK506 concentrations. We have cloned the cDNA encoding human FKBP12.6 and characterized the protein. In transfected Jurkat cells, FKBP12.6 is equivalent to FKBP12 at mediating the inhibitory effects of FK506. Upon binding rapamycin, FKBP12.6 complexes with the 288-kDa mammalian target of rapamycin. In contrast to FKBP12, FKBP12.6 is not associated with ryanodine receptor isoform-1 but with the distinct ryanodine receptor isoform-2 in cardiac muscle sarcoplasmic reticulum. Our results suggest that FKBP12.6 has both a unique physiological role in excitation-contraction coupling in cardiac muscle and the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin.
Interacting selectively and non-covalently with one or more specific sites on a receptor molecule, a macromolecule that undergoes combination with a hormone, neurotransmitter, drug or intracellular messenger to initiate a change in cell function.
Evidence
1:
Inferred from Physical InteractionBHF-UCL
The 12.6-kDa FK506-binding protein (FKBP12.6) is considered to be a key regulator of the cardiac ryanodine receptor (RyR2), but its precise role in RyR2 function is complex and controversial. In the present study we investigated the impact of FKBP12.6 removal on the properties of the RyR2 channel and the propensity for spontaneous Ca(2+) release and the occurrence of ventricular arrhythmias. Single channel recordings in lipid bilayers showed that FK506 treatment of recombinant RyR2 co-expressed with or without FKBP12.6 or native canine RyR2 did not induce long-lived subconductance states. [(3)H]Ryanodine binding studies revealed that coexpression with or without FKBP12.6 or treatment with or without FK506 did not alter the sensitivity of RyR2 to activation by Ca(2+) or caffeine. Furthermore, single cell Ca(2+) imaging analyses demonstrated that HEK293 cells co-expressing RyR2 and FKBP12.6 or expressing RyR2 alone displayed the same propensity for spontaneous Ca(2+) release or store overload-induced Ca(2+) release (SOICR). FK506 increased the amplitude and decreased the frequency of SOICR in HEK293 cells expressing RyR2 with or without FKBP12.6, indicating that the action of FK506 on SOICR is independent of FKBP12.6. As with recombinant RyR2, the conductance and ligand-gating properties of single RyR2 channels from FKBP12.6-null mice were indistinguishable from those of single wild type channels. Moreover, FKBP12.6-null mice did not exhibit enhanced susceptibility to stress-induced ventricular arrhythmias, in contrast to previous reports. Collectively, our results demonstrate that the loss of FKBP12.6 has no significant effect on the conduction and activation of RyR2 or the propensity for spontaneous Ca(2+) release and stress-induced ventricular arrhythmias.
Evidence
2:
Inferred from Physical InteractionBHF-UCL
The ryanodine receptor (RyR)/calcium release channel on the sarcoplasmic reticulum (SR) is the major source of calcium (Ca2+) required for cardiac muscle excitation-contraction (EC) coupling. The channel is a tetramer comprised of four type 2 RyR polypeptides (RyR2) and four FK506 binding proteins (FKBP12.6). We show that protein kinase A (PKA) phosphorylation of RyR2 dissociates FKBP12.6 and regulates the channel open probability (Po). Using cosedimentation and coimmunoprecipitation we have defined a macromolecular complex comprised of RyR2, FKBP12.6, PKA, the protein phosphatases PP1 and PP2A, and an anchoring protein, mAKAP. In failing human hearts, RyR2 is PKA hyperphosphorylated, resulting in defective channel function due to increased sensitivity to Ca2+-induced activation.
Contributes to ryanodine-sensitive calcium-release channel activitydefinition[GO:0005219]
Catalysis of the transmembrane transfer of a calcium ion by a channel that opens when a ryanodine class ligand has been bound by the channel complex or one of its constituent parts.
Receptor accessory peptidyl prolyl cis/trans isomerases (PPIases) of the FKBP and cyclophilin types form receptor heterocomplexes with different stabilities. PPIases have been found to associate with other receptor heterocomplex constituents via either proline-directed active sites or additional domains of the enzymes. The single-domain PPIases FKBP12 and FKBP12.6 are shown to interact with receptor protein kinases and calcium channels at their active sites. In contrast, heterooligomeric nuclear receptors contain multi-domain PPIases like FKBP51, FKBP52 or cyclophilin 40 that directly interact with the chaperone hsp90 via the tetratricopeptide repeat modules of the folding helper enzymes. PPIases play a critical role in the functional arrangement of components within receptor heterocomplexes.
Receptor accessory peptidyl prolyl cis/trans isomerases (PPIases) of the FKBP and cyclophilin types form receptor heterocomplexes with different stabilities. PPIases have been found to associate with other receptor heterocomplex constituents via either proline-directed active sites or additional domains of the enzymes. The single-domain PPIases FKBP12 and FKBP12.6 are shown to interact with receptor protein kinases and calcium channels at their active sites. In contrast, heterooligomeric nuclear receptors contain multi-domain PPIases like FKBP51, FKBP52 or cyclophilin 40 that directly interact with the chaperone hsp90 via the tetratricopeptide repeat modules of the folding helper enzymes. PPIases play a critical role in the functional arrangement of components within receptor heterocomplexes.
The regulated release of proinsulin from secretory granules (B granules) in the B cells of the pancreas; accompanied by cleavage of proinsulin to form mature insulin.
A process in which force is generated within muscle tissue, resulting in a change in muscle geometry. Force generation involves a chemo-mechanical energy conversion step that is carried out by the actin/myosin complex activity, which generates force through ATP hydrolysis.
J. Biol. Chem. 270, 26511-26522 (1995)[PubMed:7592869]
FK506, an immunosuppressant that prolongs allograft survival, is a co-drug with its intracellular receptor, FKBP12. The FKBP12.FK506 complex inhibits calcineurin, a critical signaling molecule during T-cell activation. FKBP12 was, until recently, the sole FKBP known to mediate calcineurin inhibition at clinically relevant FK506 concentrations. The best characterized cellular function of FKBP12 is the modulation of ryanodine receptor isoform-1, a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. Recently, a novel protein, FKBP12.6, was found to inhibit calcineurin at clinically relevant FK506 concentrations. We have cloned the cDNA encoding human FKBP12.6 and characterized the protein. In transfected Jurkat cells, FKBP12.6 is equivalent to FKBP12 at mediating the inhibitory effects of FK506. Upon binding rapamycin, FKBP12.6 complexes with the 288-kDa mammalian target of rapamycin. In contrast to FKBP12, FKBP12.6 is not associated with ryanodine receptor isoform-1 but with the distinct ryanodine receptor isoform-2 in cardiac muscle sarcoplasmic reticulum. Our results suggest that FKBP12.6 has both a unique physiological role in excitation-contraction coupling in cardiac muscle and the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin.
The process of assisting in the covalent and noncovalent assembly of single chain polypeptides or multisubunit complexes into the correct tertiary structure that results in the attainment of the full functional capacity of a protein.
Receptor accessory peptidyl prolyl cis/trans isomerases (PPIases) of the FKBP and cyclophilin types form receptor heterocomplexes with different stabilities. PPIases have been found to associate with other receptor heterocomplex constituents via either proline-directed active sites or additional domains of the enzymes. The single-domain PPIases FKBP12 and FKBP12.6 are shown to interact with receptor protein kinases and calcium channels at their active sites. In contrast, heterooligomeric nuclear receptors contain multi-domain PPIases like FKBP51, FKBP52 or cyclophilin 40 that directly interact with the chaperone hsp90 via the tetratricopeptide repeat modules of the folding helper enzymes. PPIases play a critical role in the functional arrangement of components within receptor heterocomplexes.
J. Biol. Chem. 270, 26511-26522 (1995)[PubMed:7592869]
FK506, an immunosuppressant that prolongs allograft survival, is a co-drug with its intracellular receptor, FKBP12. The FKBP12.FK506 complex inhibits calcineurin, a critical signaling molecule during T-cell activation. FKBP12 was, until recently, the sole FKBP known to mediate calcineurin inhibition at clinically relevant FK506 concentrations. The best characterized cellular function of FKBP12 is the modulation of ryanodine receptor isoform-1, a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. Recently, a novel protein, FKBP12.6, was found to inhibit calcineurin at clinically relevant FK506 concentrations. We have cloned the cDNA encoding human FKBP12.6 and characterized the protein. In transfected Jurkat cells, FKBP12.6 is equivalent to FKBP12 at mediating the inhibitory effects of FK506. Upon binding rapamycin, FKBP12.6 complexes with the 288-kDa mammalian target of rapamycin. In contrast to FKBP12, FKBP12.6 is not associated with ryanodine receptor isoform-1 but with the distinct ryanodine receptor isoform-2 in cardiac muscle sarcoplasmic reticulum. Our results suggest that FKBP12.6 has both a unique physiological role in excitation-contraction coupling in cardiac muscle and the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin.
Evidence
2:
Inferred from Direct AssayGOC
Evidence for Iso 1
We isolated a novel gene encoding a protein highly homologous to human FK506-binding protein 12kDa (hFKBP-12) from a human fetal brain cDNA library and determined the full-length cDNA sequence. The cDNA clone contained the open reading frame of 324 nucleotides encoding 108 amino acid and revealed 76% identity in DNA sequence and 88% identity in predicted amino acid sequence with hFKBP-12. The DNA and amino-acid sequence of this gene, designated OTK4, also had homology with other FKBPs in species ranging from humans to prokaryotes. Recombinant protein, produced in E.coli transformed by a pGEX2T expression vector containing the OTK4 cDNA and purified, showed peptidyl-prolyl cis-trans isomerase activity like other FKBP proteins. An alternatively spliced form of the transcript found in the cDNA library contained a 45-bp insertion which included a stop codon. Although the biological function of the truncated version of OTK4 is unknown, both transcripts were ubiquitously expressed in human tissues examined by the reverse-transcriptase PCR (RT-PCR) method.
Receptor accessory peptidyl prolyl cis/trans isomerases (PPIases) of the FKBP and cyclophilin types form receptor heterocomplexes with different stabilities. PPIases have been found to associate with other receptor heterocomplex constituents via either proline-directed active sites or additional domains of the enzymes. The single-domain PPIases FKBP12 and FKBP12.6 are shown to interact with receptor protein kinases and calcium channels at their active sites. In contrast, heterooligomeric nuclear receptors contain multi-domain PPIases like FKBP51, FKBP52 or cyclophilin 40 that directly interact with the chaperone hsp90 via the tetratricopeptide repeat modules of the folding helper enzymes. PPIases play a critical role in the functional arrangement of components within receptor heterocomplexes.
Regulation of cardiac muscle contraction by regulation of the release of sequestered calcium iondefinition[GO:0010881]
Any process that modulates the frequency, rate or extent of cardiac muscle contraction via the regulation of the release of sequestered calcium ion by sarcoplasmic reticulum into cytosol. The sarcoplasmic reticulum is the endoplasmic reticulum of striated muscle, specialised for the sequestration of calcium ions that are released upon receipt of a signal relayed by the T tubules from the neuromuscular junction.
ISSOrtholog Curator
Contradiction
Regulation of ryanodine-sensitive calcium-release channel activitydefinition[GO:0060314]
Any process that modulates the activity of a ryanodine-sensitive calcium-release channel. The ryanodine-sensitive calcium-release channel catalyzes the transmembrane transfer of a calcium ion by a channel that opens when a ryanodine class ligand has been bound by the channel complex or one of its constituent parts.
Negative evidence
1:
Inferred from Direct AssayBHF-UCL
The 12.6-kDa FK506-binding protein (FKBP12.6) is considered to be a key regulator of the cardiac ryanodine receptor (RyR2), but its precise role in RyR2 function is complex and controversial. In the present study we investigated the impact of FKBP12.6 removal on the properties of the RyR2 channel and the propensity for spontaneous Ca(2+) release and the occurrence of ventricular arrhythmias. Single channel recordings in lipid bilayers showed that FK506 treatment of recombinant RyR2 co-expressed with or without FKBP12.6 or native canine RyR2 did not induce long-lived subconductance states. [(3)H]Ryanodine binding studies revealed that coexpression with or without FKBP12.6 or treatment with or without FK506 did not alter the sensitivity of RyR2 to activation by Ca(2+) or caffeine. Furthermore, single cell Ca(2+) imaging analyses demonstrated that HEK293 cells co-expressing RyR2 and FKBP12.6 or expressing RyR2 alone displayed the same propensity for spontaneous Ca(2+) release or store overload-induced Ca(2+) release (SOICR). FK506 increased the amplitude and decreased the frequency of SOICR in HEK293 cells expressing RyR2 with or without FKBP12.6, indicating that the action of FK506 on SOICR is independent of FKBP12.6. As with recombinant RyR2, the conductance and ligand-gating properties of single RyR2 channels from FKBP12.6-null mice were indistinguishable from those of single wild type channels. Moreover, FKBP12.6-null mice did not exhibit enhanced susceptibility to stress-induced ventricular arrhythmias, in contrast to previous reports. Collectively, our results demonstrate that the loss of FKBP12.6 has no significant effect on the conduction and activation of RyR2 or the propensity for spontaneous Ca(2+) release and stress-induced ventricular arrhythmias.
J. Biol. Chem. 270, 26511-26522 (1995)[PubMed:7592869]
FK506, an immunosuppressant that prolongs allograft survival, is a co-drug with its intracellular receptor, FKBP12. The FKBP12.FK506 complex inhibits calcineurin, a critical signaling molecule during T-cell activation. FKBP12 was, until recently, the sole FKBP known to mediate calcineurin inhibition at clinically relevant FK506 concentrations. The best characterized cellular function of FKBP12 is the modulation of ryanodine receptor isoform-1, a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. Recently, a novel protein, FKBP12.6, was found to inhibit calcineurin at clinically relevant FK506 concentrations. We have cloned the cDNA encoding human FKBP12.6 and characterized the protein. In transfected Jurkat cells, FKBP12.6 is equivalent to FKBP12 at mediating the inhibitory effects of FK506. Upon binding rapamycin, FKBP12.6 complexes with the 288-kDa mammalian target of rapamycin. In contrast to FKBP12, FKBP12.6 is not associated with ryanodine receptor isoform-1 but with the distinct ryanodine receptor isoform-2 in cardiac muscle sarcoplasmic reticulum. Our results suggest that FKBP12.6 has both a unique physiological role in excitation-contraction coupling in cardiac muscle and the potential to contribute to the immunosuppressive and toxic effects of FK506 and rapamycin.
The 12.6-kDa FK506-binding protein (FKBP12.6) is considered to be a key regulator of the cardiac ryanodine receptor (RyR2), but its precise role in RyR2 function is complex and controversial. In the present study we investigated the impact of FKBP12.6 removal on the properties of the RyR2 channel and the propensity for spontaneous Ca(2+) release and the occurrence of ventricular arrhythmias. Single channel recordings in lipid bilayers showed that FK506 treatment of recombinant RyR2 co-expressed with or without FKBP12.6 or native canine RyR2 did not induce long-lived subconductance states. [(3)H]Ryanodine binding studies revealed that coexpression with or without FKBP12.6 or treatment with or without FK506 did not alter the sensitivity of RyR2 to activation by Ca(2+) or caffeine. Furthermore, single cell Ca(2+) imaging analyses demonstrated that HEK293 cells co-expressing RyR2 and FKBP12.6 or expressing RyR2 alone displayed the same propensity for spontaneous Ca(2+) release or store overload-induced Ca(2+) release (SOICR). FK506 increased the amplitude and decreased the frequency of SOICR in HEK293 cells expressing RyR2 with or without FKBP12.6, indicating that the action of FK506 on SOICR is independent of FKBP12.6. As with recombinant RyR2, the conductance and ligand-gating properties of single RyR2 channels from FKBP12.6-null mice were indistinguishable from those of single wild type channels. Moreover, FKBP12.6-null mice did not exhibit enhanced susceptibility to stress-induced ventricular arrhythmias, in contrast to previous reports. Collectively, our results demonstrate that the loss of FKBP12.6 has no significant effect on the conduction and activation of RyR2 or the propensity for spontaneous Ca(2+) release and stress-induced ventricular arrhythmias.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a glucose stimulus.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a hydrogen peroxide (H2O2) stimulus.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus indicating redox state. Redox state refers to the balance of oxidized versus reduced forms of electron donors and acceptors in an organelle, cell or organ; plastoquinone, glutathione (GSH/GSSG), and nicotinamide nucleotides (NAD+/NADH and NADP+/NADPH) are among the most important.
In the present paper we show that distinct human RyR2 (ryanodine receptor type 2) inherited mutations expressed in mammalian cells exhibit either unaltered or increased FKBP12.6 (12.6 kDa FK506-binding protein) binding compared with the wild-type. Oxidizing conditions result in decreased FKBP12.6 binding, but to the same extent as for the wild-type. Our findings suggest that FKBP12.6 regulation of RyR2 is unlikely to be the primary defect in inherited arrhythmogenic cardiac disease.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a vitamin E stimulus.
A process in which force is generated within smooth muscle tissue, resulting in a change in muscle geometry. Force generation involves a chemo-mechanical energy conversion step that is carried out by the actin/myosin complex activity, which generates force through ATP hydrolysis. Smooth muscle differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length.
Enzyme that catalyzes the 1,1-, 1,2- or 1,3-hydrogen shift. The 1,1- hydrogen shift is an inversion at an asymmetric carbon center (racemases, epimerases). The 1,2-hydrogen shift involved a hydrogen transfer between two adjacent carbon atoms, one undergoing oxidation, the other reduction (aldose-ketose isomerases). The 1,3-hydrogen shifts are allylic or azaallylic (when nitrogen is one of the three atoms) isomerizations.
Enzyme (EC 5.2.1.8) which accelerates the folding of proteins by catalyzing the cis-trans isomerization of proline imidic peptide bonds in oligopeptides.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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