共查询到20条相似文献,搜索用时 15 毫秒
1.
Philipp O. Tsvetkov Alexandra A. Kulikova Yaroslav V. Tkachev Sergey A. Kozin Alexander A. Makarov 《Biophysical journal》2010,99(10):L84
Zinc-induced aggregation of amyloid-β peptide (Aβ) is a hallmark molecular feature of Alzheimer's disease. Here we provide direct thermodynamic evidence that elucidates the role of the Aβ region 6-14 as the minimal Zn2+ binding site wherein the ion is coordinated by His6, Glu11, His13, and His14. With the help of isothermal titration calorimetry and quantum mechanics/molecular mechanics simulations, the region 11-14 was determined as the primary zinc recognition site and considered an important drug-target candidate to prevent Zn2+-induced aggregation of Aβ. 相似文献
2.
Jingxin Chen Katie L. Winarski Mike M. Myerburg Bruce R. Pitt Shaohu Sheng 《The Journal of biological chemistry》2012,287(42):35589-35598
Extracellular Zn2+ activates the epithelial Na+ channel (ENaC) by relieving Na+ self-inhibition. However, a biphasic Zn2+ dose response was observed, suggesting that Zn2+ has dual effects on the channel (i.e. activating and inhibitory). To investigate the structural basis for this biphasic effect of Zn2+, we examined the effects of mutating the 10 extracellular His residues of mouse γENaC. Four mutations within the finger subdomain (γH193A, γH200A, γH202A, and γH239A) significantly reduced the maximal Zn2+ activation of the channel. Whereas γH193A, γH200A, and γH202A reduced the apparent affinity of the Zn2+ activating site, γH239A diminished Na+ self-inhibition and thus concealed the activating effects of Zn2+. Mutation of a His residue within the palm subdomain (γH88A) abolished the low-affinity Zn2+ inhibitory effect. Based on structural homology with acid-sensing ion channel 1, γAsp516 was predicted to be in close proximity to γHis88. Ala substitution of the residue (γD516A) blunted the inhibitory effect of Zn2+. Our results suggest that external Zn2+ regulates ENaC activity by binding to multiple extracellular sites within the γ-subunit, including (i) a high-affinity stimulatory site within the finger subdomain involving His193, His200, and His202 and (ii) a low-affinity Zn2+ inhibitory site within the palm subdomain that includes His88 and Asp516. 相似文献
3.
Evan Q. Comeaux Selma M. Cuya Kyoko Kojima Nauzanene Jafari Keith C. Wanzeck James A. Mobley Mary-Ann Bjornsti Robert C. A. M. van Waardenburg 《The Journal of biological chemistry》2015,290(10):6203-6214
Tyrosyl-DNA phosphodiesterase I (Tdp1) catalyzes the repair of 3′-DNA adducts, such as the 3′-phosphotyrosyl linkage of DNA topoisomerase I to DNA. Tdp1 contains two conserved catalytic histidines: a nucleophilic His (Hisnuc) that attacks DNA adducts to form a covalent 3′-phosphohistidyl intermediate and a general acid/base His (Hisgab), which resolves the Tdp1-DNA linkage. A Hisnuc to Ala mutant protein is reportedly inactive, whereas the autosomal recessive neurodegenerative disease SCAN1 has been attributed to the enhanced stability of the Tdp1-DNA intermediate induced by mutation of Hisgab to Arg. However, here we report that expression of the yeast HisnucAla (H182A) mutant actually induced topoisomerase I-dependent cytotoxicity and further enhanced the cytotoxicity of Tdp1 Hisgab mutants, including H432N and the SCAN1-related H432R. Moreover, the HisnucAla mutant was catalytically active in vitro, albeit at levels 85-fold less than that observed with wild type Tdp1. In contrast, the HisnucPhe mutant was catalytically inactive and suppressed Hisgab mutant-induced toxicity. These data suggest that the activity of another nucleophile when Hisnuc is replaced with residues containing a small side chain (Ala, Asn, and Gln), but not with a bulky side chain. Indeed, genetic, biochemical, and mass spectrometry analyses show that a highly conserved His, immediately N-terminal to Hisnuc, can act as a nucleophile to catalyze the formation of a covalent Tdp1-DNA intermediate. These findings suggest that the flexibility of Tdp1 active site residues may impair the resolution of mutant Tdp1 covalent phosphohistidyl intermediates and provide the rationale for developing chemotherapeutics that stabilize the covalent Tdp1-DNA intermediate. 相似文献
4.
Recent reports show that heme binds to amyloid β-peptide (Aβ) in the brain of Alzheimer’s disease (AD) patients and forms Aβ–heme complexes, thus leading a pathological feature of AD. However, the important biological relevance to AD etiology, resulting from human Aβ–heme peroxidase formation, was not well characterized. In this study, we used wild-type and mutated human Aβ1–16 peptides and investigated their Aβ–heme peroxidase activities. Our results indicated that both histidine residues (His13, His14) in Aβ1–16 and free histidine enhanced the peroxidase activity of heme, hence His residues were essential in peroxidase activity of Aβ–heme complexes. Moreover, Arg5 was found to be the key residue in making the Aβ1–16–heme complex as a peroxidase. Under oxidative and nitrative stress conditions, the Aβ1–16–heme complexes caused oxidation and nitration of the Aβ Tyr10 residue through promoting peroxidase-like reactions. Therefore, these residues (Arg5, Tyr10 and His) were pivotal in human Aβ–heme peroxidase activity. However, three of these residues (Arg5, Tyr10 and His13) identified in this study are all absent in rodents, where rodent Aβ–heme complex lacks peroxidase activity and it does not show AD, implicating the novel significance of these residues as well as human Aβ–heme peroxidase in the pathology of AD. 相似文献
5.
《Biochimica et Biophysica Acta (BBA)/General Subjects》2016,1860(4):719-726
BackgroundThe misfolding of human islet amyloid polypeptide (hIAPP) is an important pathological factor on the onset of type 2 diabetes. A number of studies have been focused on His18, the only histidine of hIAPP, whose imidazole ring and the protonation state might impact hIAPP amyloid formation, but the exact mechanism remains unclear.MethodsWe used diethylpyrocarbonate (DEPC) to specifically modify His18 and obtained mono-ethyloxyformylated hIAPP (DMI). Thioflavin T based fluorescence, transmission electronic microscopy, circular dichroism spectroscopy, fluorescence dye leakage, Fourier transform infrared spectroscopy and replica-exchange molecular dynamics (REMD) simulation were applied to study the impact of DEPC-modification on hIAPP amyloid formation.ResultsAfter an ethyl-acetate group was introduced to the His18 of hIAPP by diethylpyrocarbonate (DEPC) modification, the pH dependent hIAPP fibrillation went to the opposite order and the number of intra-molecular hydrogen bonds decreased, while the possibility of His18 participating in the formation of α-helical structures increased. Furthermore, the membrane–peptide interaction and ion–peptide interaction were both impaired.ConclusionsThe intramolecular hydrogen bond formation by His18 and the possibility of His18 participating in the formation of α-helical structures greatly modulated the manner of hIAPP amyloid formation. The imidazole ring directly participates in the hIAPP–membrane/ion interaction.General significanceDEPC modification is an alternative approach to investigate the role of the imidazole ring during amyloid formation. 相似文献
6.
New dihydropyrimidines bearing various lipophilic pharmacophores and functionalities at position 3 were designed and synthesized. The basic framework of the new compounds was designed to maintain the main structural requirements for calcium channel blocking activity of the known dihydropyridines and dihydropyrimidines calcium channel blockers. The newly synthesized compounds were evaluated as antagonists for CaV1.2 and CaV3.2 using the whole-cell patch clamp technique. Seven compounds (4b, 4c, 6c, 9, 13c, 13e and 17b) showed promising dual calcium channel blocking activity and three compounds (13b, 14b and 17a) were selective against Cav3.2. Their drug-likeness has been assessed using Molinspiration and Molsoft softwares. Their physicochemical properties and pharmacokinetic profiles recommend that they can be considered as drug-like candidates. 相似文献
7.
《Biochimica et Biophysica Acta (BBA)/General Subjects》2014,1840(9):2886-2903
BackgroundAlzheimer's disease (AD) is a progressive neurodegenerative brain disorder that is characterized by dementia, cognitive impairment, and memory loss. Diverse factors are related to the development of AD, such as increased level of β-amyloid (Aβ), acetylcholine, metal ion deregulation, hyperphosphorylated tau protein, and oxidative stress.MethodsThe following methods were used: organic syntheses of 1H-phenanthro[9,10-d]imidazole derivatives, inhibition of self-mediated and metal-induced Aβ1–42 aggregation, inhibition studies for acetylcholinesterase and butyrylcholinesterase, anti-oxidation activity studies, CD, MTT assay, transmission electron microscopy, dot plot assay, gel electrophoresis, Western blot, and molecular docking studies.ResultsWe synthesized and characterized a new type of 1H-phenanthro[9,10-d]imidazole derivatives as multifunctional agents for AD treatment. Our results showed that most of these derivatives exhibited strong Aβ aggregation inhibitory activity. Compound 9g had 74% Aβ1–42 aggregation inhibitory effect at 10 μM concentration with its IC50 value of 6.5 μM for self-induced Aβ1–42 aggregation. This compound also showed good inhibition of metal-mediated (Cu2 + and Fe2 +) and acetylcholinesterase-induced Aβ1–42 aggregation, as indicated by using thioflavin T assay, transmission electron microscopy, gel electrophoresis, and Western blot. Besides, compound 9g exhibited cholinesterase inhibitory activity, with its IC50 values of 0.86 μM and 0.51 μM for acetylcholinesterase and butyrylcholinesterase, respectively. In addition, compound 9g showed good anti-oxidation effect with oxygen radical absorbance capacity (ORAC) value of 2.29.ConclusionsCompound 9g was found to be a potent multi-target-directed agent for Alzheimer's disease.General significanceCompound 9g could become a lead compound for further development as a multi-target-directed agent for AD treatment. 相似文献
8.
Hyunbum Jang Fernando Teran Arce Srinivasan Ramachandran Ruth Nussinov 《Biophysical journal》2009,97(11):3029-3037
In Alzheimer's disease, calcium permeability through cellular membranes appears to underlie neuronal cell death. It is increasingly accepted that calcium permeability involves toxic ion channels. We modeled Alzheimer's disease ion channels of different sizes (12-mer to 36-mer) in the lipid bilayer using molecular dynamics simulations. Our Aβ channels consist of the solid-state NMR-based U-shaped β-strand-turn-β-strand motif. In the simulations we obtain ion-permeable channels whose subunit morphologies and shapes are consistent with electron microscopy/atomic force microscopy. In agreement with imaged channels, the simulations indicate that β-sheet channels break into loosely associated mobile β-sheet subunits. The preferred channel sizes (16- to 24-mer) are compatible with electron microscopy/atomic force microscopy-derived dimensions. Mobile subunits were also observed for β-sheet channels formed by cytolytic PG-1 β-hairpins. The emerging picture from our large-scale simulations is that toxic ion channels formed by β-sheets spontaneously break into loosely interacting dynamic units that associate and dissociate leading to toxic ionic flux. This sharply contrasts intact conventional gated ion channels that consist of tightly interacting α-helices that robustly prevent ion leakage, rather than hydrogen-bonded β-strands. The simulations suggest why conventional gated channels evolved to consist of interacting α-helices rather than hydrogen-bonded β-strands that tend to break in fluidic bilayers. Nature designs folded channels but not misfolded toxic channels. 相似文献
9.
Youhei Sohma Qing-xin Hua Ming Liu Nelson B. Phillips Shi-Quan Hu Jonathan Whittaker Linda J. Whittaker Aubree Ng Charles T. Roberts Jr Peter Arvan Stephen B. H. Kent Michael A. Weiss 《The Journal of biological chemistry》2010,285(7):5040-5055
Proinsulin exhibits a single structure, whereas insulin-like growth factors refold as two disulfide isomers in equilibrium. Native insulin-related growth factor (IGF)-I has canonical cystines (A6—A11, A7–B7, and A20—B19) maintained by IGF-binding proteins; IGF-swap has alternative pairing (A7–A11, A6—B7, and A20—B19) and impaired activity. Studies of mini-domain models suggest that residue B5 (His in insulin and Thr in IGFs) governs the ambiguity or uniqueness of disulfide pairing. Residue B5, a site of mutation in proinsulin causing neonatal diabetes, is thus of broad biophysical interest. Here, we characterize reciprocal B5 substitutions in the two proteins. In insulin, HisB5 → Thr markedly destabilizes the hormone (ΔΔGu 2.0 ± 0.2 kcal/mol), impairs chain combination, and blocks cellular secretion of proinsulin. The reciprocal IGF-I substitution ThrB5 → His (residue 4) specifies a unique structure with native 1H NMR signature. Chemical shifts and nuclear Overhauser effects are similar to those of native IGF-I. Whereas wild-type IGF-I undergoes thiol-catalyzed disulfide exchange to yield IGF-swap, HisB5-IGF-I retains canonical pairing. Chemical denaturation studies indicate that HisB5 does not significantly enhance thermodynamic stability (ΔΔGu 0.2 ± 0.2 kcal/mol), implying that the substitution favors canonical pairing by destabilizing competing folds. Whereas the activity of ThrB5-insulin is decreased 5-fold, HisB5-IGF-I exhibits 2-fold increased affinity for the IGF receptor and augmented post-receptor signaling. We propose that conservation of ThrB5 in IGF-I, rescued from structural ambiguity by IGF-binding proteins, reflects fine-tuning of signal transduction. In contrast, the conservation of HisB5 in insulin highlights its critical role in insulin biosynthesis. 相似文献
10.
N. Thibault G. Peytavin J. R. Claude 《Journal of biochemical and molecular toxicology》1991,6(3):237-238
The effect on acetaminophen-induced cytotoxicity of three calcium channel blocking agents-diltiazem, verapamil and gallopamil-was studied in primary cultures of rat hepatocytes and compared with the chelating agent EGTA. Using the measurement of cytosolic lactate dehydrogenase (LDH) as an index of cytotoxicity, it was demonstrated that a 1-hr pretreatment with calcium channel blocking agents protected cells against acetaminophen cytotoxicity, but were less effective than EGTA. These data suggest that influx of extracellular Ca2+ into the cells could have a role in the genesis of hepatocyte injury by acetaminophen. 相似文献
11.
Christian Reichen Chaithanya Madhurantakam Andreas Plückthun Peer R. E. Mittl 《Protein science : a publication of the Protein Society》2014,23(11):1572-1583
Designed armadillo repeat proteins (dArmRP) are promising modular proteins for the engineering of binding molecules that recognize extended polypeptide chains. We determined the structure of a dArmRP containing five internal repeats and 3rd generation capping repeats in three different states by X‐ray crystallography: without N‐terminal His6‐tag and in the presence of calcium (YM5A/Ca2+), without N‐terminal His6‐tag and in the absence of calcium (YM5A), and with N‐terminal His6‐tag and in the presence of calcium (His‐YM5A/Ca2+). All structures show different quaternary structures and superhelical parameters. His‐YM5A/Ca2+ forms a crystallographic dimer, which is bridged by the His6‐tag, YM5A/Ca2+ forms a domain‐swapped tetramer, and only in the absence of calcium and the His6‐tag, YM5A forms a monomer. The changes of superhelical parameters are a consequence of calcium binding, because calcium ions interact with negatively charged residues, which can also participate in the modulation of helix dipole moments between adjacent repeats. These observations are important for further optimizations of dArmRPs and provide a general illustration of how construct design and crystallization conditions can influence the exact structure of the investigated protein. 相似文献
12.
Katie L. Winarski Nan Sheng Jingxin Chen Thomas R. Kleyman Shaohu Sheng 《The Journal of biological chemistry》2010,285(34):26088-26096
The activity of the epithelial Na+ channel (ENaC) is modulated by Na+ self-inhibition, a down-regulation of the open probability of ENaC by extracellular Na+. A His residue within the extracellular domain of γENaC (γHis239) was found to have a critical role in Na+ self-inhibition. We investigated the functional roles of residues in the vicinity of this His by mutagenesis and analyses of Na+ self-inhibition responses in Xenopus oocytes. Significant changes in the speed and magnitude of Na+ self-inhibition were observed in 16 of the 47 mutants analyzed. These 16 mutants were distributed within a 22-residue tract. We further characterized this scanned region by examining the accessibility of introduced Cys residues to the sulfhydryl reagent MTSET. External MTSET irreversibly increased or decreased currents in 13 of 47 mutants. The distribution patterns of the residues where substitutions significantly altered Na+ self-inhibition or/and conferred sensitivity to MTSET were consistent with the existence of two helices within this region. In addition, single channel recordings of the γH239F mutant showed that, in the absence of Na+ self-inhibition and with an increased open probability, ENaCs still undergo transitions between open and closed states. We conclude that γHis239 functions within an extracellular allosteric regulatory subdomain of the γ subunit that has an important role in conferring the response of the channel to external Na+. 相似文献
13.
Streltsov VA Titmuss SJ Epa VC Barnham KJ Masters CL Varghese JN 《Biophysical journal》2008,95(7):3447-3456
Neurodegeneration observed in Alzheimer disease (AD) is believed to be related to the toxicity from reactive oxygen species (ROS) produced in the brain by the amyloid-β (Aβ) protein bound primarily to copper ions. The evidence for an oxidative stress role of Aβ-Cu redox chemistry is still incomplete. Details of the copper binding site in Aβ may be critical to the etiology of AD. Here we present the structure determined by combining x-ray absorption spectroscopy (XAS) and density functional theory analysis of Aβ peptides complexed with Cu2+ in solution under a range of buffer conditions. Phosphate-buffered saline buffer salt (NaCl) concentration does not affect the high-affinity copper binding mode but alters the second coordination sphere. The XAS spectra for truncated and full-length Aβ-Cu2+ peptides are similar. The novel distorted six-coordinated (3N3O) geometry around copper in the Aβ-Cu2+ complexes include three histidines: glutamic, or/and aspartic acid, and axial water. The structure of the high-affinity Cu2+ binding site is consistent with the hypothesis that the redox activity of the metal ion bound to Aβ can lead to the formation of dityrosine-linked dimers found in AD. 相似文献
14.
Dang LT Purvis AR Huang RH Westfield LA Sadler JE 《The Journal of biological chemistry》2011,286(29):25763-25769
von Willebrand factor (VWF) is a multimeric plasma protein that mediates platelet adhesion to sites of vascular injury. The hemostatic function of VWF depends upon the formation of disulfide-linked multimers, which requires the VWF propeptide (D1D2 domains) and adjacent D′D3 domains. VWF multimer assembly occurs in the trans-Golgi at pH ∼6.2 but not at pH 7.4, which suggests that protonation of one or more His residues (pKa ∼6.0) mediates the pH dependence of multimerization. Alignment of 30 vertebrate VWF sequences identified 13 highly conserved His residues in the D1D2D′D3 domains, and His-to-Ala mutagenesis identified His395 and His460 in the D2 domain as critical for VWF multimerization. Replacement of His395 with Lys or Arg prevented multimer assembly, suggesting that reversible protonation of this His residue is essential. In contrast, replacement of His460 with Lys or Arg preserved normal multimer assembly, whereas Leu, Met, and Gln did not, indicating that the function of His460 depends primarily upon the presence of a positive charge. These results suggest that pH sensing by evolutionarily conserved His residues facilitates the assembly and packaging of VWF multimers upon arrival in the trans-Golgi. 相似文献
15.
Yifan Zhao Feng Ye Jian Xu Qinghong Liao Lei Chen Weijia Zhang Haopeng Sun Wenyuan Liu Feng Feng Wei Qu 《Bioorganic & medicinal chemistry》2018,26(13):3812-3824
To develop potent multi-target ligands against Alzheimer's disease (AD), a series of novel bivalent β-carboline derivatives were designed, synthesized, and evaluated. In vitro studies revealed these compounds exhibited good multifunctional activities. In particular, compounds 8f and 8g showed the good selectivity potency on BuChE inhibition (IC50?=?1.7 and 2.7?μM, respectively), Aβ1-42 disaggregation and neuroprotection. Compared with the positive control resveratrol, 8f and 8g showed better activity in inhibiting Aβ1-42 aggregation, with inhibitory rate 82.7% and 85.7% at 25?μM, respectively. Moreover, compounds 8e, 8f and 8g displayed excellent neuroprotective activity by ameliorating the impairment induced by H2O2, okadaic acid (OA) and Aβ1-42 without cytotoxicity in SH-SY5Y cells. Thus, the present study evidently showed that compounds 8f and 8g are potent multi-functional agents against AD and might serve as promising lead candidates for further development. 相似文献
16.
In previous work, decolorization of malachite green (MG) was studied in Aspergillus niger in the presence and absence of calcium chloride stress. Decolorization took place within 24 h, and a signal transduction process that initiated MG decolorization was suggested to be involved. In the present study, further investigation of the relationship between calcium chloride stress and enhanced MG biodegradation was conducted at the sub-cellular level. MG-NADH reductase activity, a key enzyme in MG decolorization, was produced as decolorization commenced, and enzyme activity increased threefold upon exposure to calcium chloride. Inhibitors of cytochrome p450, Ca2+ channel activity as well as activity of the signaling protein phosphoinositide 3-kinase were tested. All three activities were inhibited to different extents resulting in reduced MG decolorization. Spectral analysis of the mitochondrial fraction showed a heme signal at 405 nm and A405/A280 ratio that is characteristic of the porphoryin ring of cytochromes. There were no peaks detected for cytochromes a or b, but a shoulder appearing at 550 nm was observed, which suggested that cytochrome c is involved; the absorbance for cytochrome c doubled after calcium chloride stress supporting this idea. MG decolorization took place via a series of demethylation steps, and cytotoxicity analysis revealed a decrease in the toxicity associated with generation of leucomalachite green. 相似文献
17.
18.
Molecular dynamics trajectories 2 μs in length have been generated for the pH-activated, tetrameric M2 proton channel of the influenza A virus in all protonation states of the pH sensor located at the His37 tetrad. All simulated structures are in very good agreement with high-resolution structures. Changes in the channel caused by progressive protonation of His37 provide insight into the mechanism of proton transport. The channel is closed at both His37 and Trp41 sites in the singly and doubly protonated states, but it opens at Trp41 upon further protonation. Anions access the charged His37 and by doing so stabilize the protonated states of the channel. The narrow opening at the His37 site, further blocked by anions, is inconsistent with the water-wire mechanism of proton transport. Instead, conformational interconversions of His37 correlated with hydrogen bonding to water molecules indicate that these residues shuttle protons in high-protonation states. Hydrogen bonds between charged and uncharged histidines are rare. The valve at Val27 remains on average quite narrow in all protonation states but fluctuates sufficiently to support water and proton transport. A proton transport mechanism in which the channel, depending on pH, opens at either the histidine or valine gate is only partially supported by the simulations. 相似文献
19.
Theun de Groot Sjoerd Verkaart Qi Xi René J. M. Bindels Joost G. J. Hoenderop 《The Journal of biological chemistry》2010,285(37):28481-28487
The epithelial Ca2+ channel TRPV5 constitutes the apical entry gate for Ca2+ transport in renal epithelial cells. Ablation of the trpv5 gene in mice leads to a reduced Ca2+ reabsorption. TRPV5 is tightly regulated by various calciotropic hormones, associated proteins, and other factors, which mainly affect channel activity via the C terminus. To further identify the role of the C terminus in TRPV5 regulation, we expressed channels harboring C-terminal deletions and studied channel activity by measuring intracellular Ca2+ concentration ([Ca2+]i) using fura-2 analysis. Removal of amino acid His712 elevated the [Ca2+]i, indicating enlarged TRPV5 activity. In addition, substitution of the positively charged His712 for a negative (H712D) or neutral (H712N) amino acid also stimulated TRPV5 activity. This critical role of His712 was confirmed by patch clamp analysis, which demonstrates increased Na+ and Ca2+ currents for TRPV5-H712D. Cell surface biotinylation studies revealed enhanced plasma membrane expression of TRPV5-H712D as compared with wild-type (WT) TRPV5. This elevated plasma membrane presence also was observed with the Ca2+-impermeable TRPV5-H712D and TRPV5-WT pore mutants, demonstrating that the elevation is not due to the increased [Ca2+]i. Finally, using an internalization assay, we demonstrated a delayed cell surface retrieval for TRPV5-H712D, likely causing the increase in plasma membrane expression. Together, these results demonstrate that His712 plays an essential role in plasma membrane regulation of TRPV5 via a constitutive endocytotic mechanism. 相似文献
20.
Erick O. Hernández-Ochoa Rotimi O. Olojo Robyn T. Rebbeck Angela F. Dulhunty Martin F. Schneider 《Biophysical journal》2014
The α1 and β1a subunits of the skeletal muscle calcium channel, Cav1.1, as well as the Ca2+ release channel, ryanodine receptor (RyR1), are essential for excitation-contraction coupling. RyR1 channel activity is modulated by the β1a subunit and this effect can be mimicked by a peptide (β1a490–524) corresponding to the 35-residue C-terminal tail of the β1a subunit. Protein-protein interaction assays confirmed a high-affinity interaction between the C-terminal tail of the β1a and RyR1. Based on previous results using overlapping peptides tested on isolated RyR1, we hypothesized that a 19-amino-acid residue peptide (β1a490–508) is sufficient to reproduce activating effects of β1a490–524. Here we examined the effects of β1a490–508 on Ca2+ release and Ca2+ currents in adult skeletal muscle fibers subjected to voltage-clamp and on RyR1 channel activity after incorporating sarcoplasmic reticulum vesicles into lipid bilayers. β1a490–508 (25 nM) increased the peak Ca2+ release flux by 49% in muscle fibers. Considerably fewer activating effects were observed using 6.25, 100, and 400 nM of β1a490–508 in fibers. β1a490–508 also increased RyR1 channel activity in bilayers and Cav1.1 currents in fibers. A scrambled form of β1a490–508 peptide was used as negative control and produced negligible effects on Ca2+ release flux and RyR1 activity. Our results show that the β1a490–508 peptide contains molecular components sufficient to modulate excitation-contraction coupling in adult muscle fibers. 相似文献