Page last updated: 2024-10-24

contractile muscle fiber

Definition

Target type: cellularcomponent

Fibers, composed of actin, myosin, and associated proteins, found in cells of smooth or striated muscle. [GOC:go_curators, ISBN:0815316194]

Contractile muscle fibers, also known as myofibers, are highly specialized elongated cells responsible for muscle contraction. They are composed of multiple cellular components that work together to generate force and movement. These components can be broadly categorized into three main levels:

1. **Myofibrils:** These are the fundamental units of muscle contraction, composed of repeating units called sarcomeres. Sarcomeres are the basic functional unit of a muscle fiber and consist of two primary protein filaments:
* **Actin filaments:** Thin filaments that are composed of the protein actin. They are anchored to the Z-discs, which are structural proteins that define the boundaries of a sarcomere.
* **Myosin filaments:** Thick filaments that are composed of the protein myosin. They are responsible for generating the force needed for muscle contraction.

2. **Sarcolemma:** This is the plasma membrane of a muscle fiber. It surrounds the myofibrils and plays a crucial role in transmitting nerve impulses to initiate muscle contraction. The sarcolemma is also involved in regulating the passage of ions and nutrients into and out of the muscle fiber.

3. **Sarcoplasmic reticulum:** This is a specialized network of intracellular membranes that surrounds each myofibril. It is responsible for storing and releasing calcium ions, which are essential for muscle contraction. The sarcoplasmic reticulum contains specialized structures called terminal cisternae, which are located near the T-tubules (transverse tubules).

**T-tubules:** These are invaginations of the sarcolemma that extend deep into the muscle fiber. They play a vital role in transmitting the nerve impulse from the sarcolemma to the sarcoplasmic reticulum, triggering the release of calcium ions and initiating muscle contraction.

These components work in a coordinated manner to generate force and movement. Upon receiving a nerve impulse, the sarcolemma depolarizes, which triggers the release of calcium ions from the sarcoplasmic reticulum. Calcium ions bind to troponin, a protein associated with the actin filaments. This binding causes a conformational change in troponin, which in turn moves tropomyosin, another protein associated with actin, out of the way. This exposes the myosin-binding sites on actin, allowing myosin to bind and initiate the sliding filament mechanism, leading to muscle contraction.

In summary, the cellular components of a contractile muscle fiber include myofibrils, sarcolemma, sarcoplasmic reticulum, T-tubules, and the various proteins that compose these structures. Each component plays a specific role in ensuring the proper function of the muscle fiber, allowing for the generation of force and movement.'
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Proteins (2)

ProteinDefinitionTaxonomy
Cyclin-dependent kinase 5 activator 1A cyclin-dependent kinase 5 activator 1 that is encoded in the genome of human. [PRO:DNx]Homo sapiens (human)
Gap junction alpha-1 proteinA gap junction alpha-1 protein that is encoded in the genome of human. [PRO:DNx, UniProtKB:P17302]Homo sapiens (human)

Compounds (78)

CompoundDefinitionClassesRoles
tacrinetacrine : A member of the class of acridines that is 1,2,3,4-tetrahydroacridine substituted by an amino group at position 9. It is used in the treatment of Alzheimer's disease.

Tacrine: A cholinesterase inhibitor that crosses the blood-brain barrier. Tacrine has been used to counter the effects of muscle relaxants, as a respiratory stimulant, and in the treatment of Alzheimer's disease and other central nervous system disorders.
acridines;
aromatic amine
EC 3.1.1.7 (acetylcholinesterase) inhibitor
gw8510GW8510: 3' substituted indolone as a scaffold for the development of neuroprotective drug; structure in first source
indirubin-3'-monoximeindirubin-3'-monoxime : A member of the class of biindoles that is indirubin in which the keto group at position 3' has undergone condensation with hydroxylamine to form the corresponding oxime.

indirubin-3'-monoxime: has antiangiogenic activity
indirubin-5-sulfonate
nsc 664704kenpaullone : An indolobenzazepine that is paullone in which the hydrogen at position 9 is replaced by a bromo substituent. It is an ATP-competitive inhibitor of cyclin-dependent kinases (CDKs) and glycogen synthase kinase 3beta (GSK3beta).

kenpaullone: inhibits CDK1/cyclin B; structure in first source
indolobenzazepine;
lactam;
organobromine compound
cardioprotective agent;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.11.26 (tau-protein kinase) inhibitor;
geroprotector
nu6102NU6102: structure in first source
olomoucineolomoucine : A 9H-purine that is substituted by a (2-hydroxyethyl)nitrilo, benzylnitrilo and a methyl group at positions 2,6 and 9, respectively. It is a cyclin-dependent kinase inhibitor.

olomoucine: inhibits protein P34CDC2
2,6-diaminopurines;
ethanolamines
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
kanamycin akanamycin : Kanamycin is a naturally occurring antibiotic complex from Streptomyces kanamyceticus that consists of several components: kanamycin A, the major component (also usually designated as kanamycin), and kanamycins B, C, D and X the minor components.

Kanamycin: Antibiotic complex produced by Streptomyces kanamyceticus from Japanese soil. Comprises 3 components: kanamycin A, the major component, and kanamycins B and C, the minor components.
kanamycinsbacterial metabolite
indirubin
indigohydroxyindoles
2-phenylindolealpha-phenylindole: RN given refers to parent cpdphenylindole
staurosporineindolocarbazole alkaloid;
organic heterooctacyclic compound
apoptosis inducer;
bacterial metabolite;
EC 2.7.11.13 (protein kinase C) inhibitor;
geroprotector
cercosporamidecercosporamide : A member of the class of dibenzofurans that is a potent broad spectrum antifungal agent isolated from the fungus Cercosporidium henningsii.

cercosporamide: antineoplastic; RN refers to (S)-isomer
dibenzofurans;
methyl ketone;
monocarboxylic acid amide;
polyphenol
antifungal agent;
EC 2.7.11.24 (mitogen-activated protein kinase) inhibitor;
fungal metabolite;
phytotoxin
birb 796aromatic ether;
morpholines;
naphthalenes;
pyrazoles;
ureas
EC 2.7.11.24 (mitogen-activated protein kinase) inhibitor;
immunomodulator
cyc 202seliciclib : 2,6-Diaminopurine carrying benzylamino, (2R)-1-hydroxybutan-2-yl and isopropyl substituents at C-6, C-2-N and N-9 respectively. It is an experimental drug candidate in the family of pharmacological cyclin-dependent kinase (CDK) inhibitors.2,6-diaminopurinesantiviral drug;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
paullonepaullone : An indolobenzazepine that is 5,6,7,12-tetrahydroindolo[3,2-d][1]benzazepine carrying an oxo substituent at position 6.

paullone: structure in first source
indolobenzazepine;
lactam
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.11.26 (tau-protein kinase) inhibitor
meridianin gmeridianin G: from the tunicate Aplidium meridianum; structure in first source
5-iodoindirubin-3'-monoxime5-iodoindirubin-3'-monoxime: inhibits GSK-3beta
2H-pyrazolo[4,3-b]quinoxalin-3-aminequinoxaline derivative
n-(4-methoxybenzyl)-n'-(5-nitro-1,3-thiazol-2-yl)ureaN-(4-methoxybenzyl)-N'-(5-nitro-1,3-thiazol-2-yl)urea: structure in first source
7-n-butyl-6-(4'-hydroxyphenyl)-5h-pyrrolo(2,3b)pyrazine
6-bromoindirubin-3'-oxime6-bromoindirubin-3'-oxime : A member of the class of biindoles that is indirubin substituted at position 6 by a bromo group and in which the keto group at position 3' has undergone condensation with hydroxylamine to form the corresponding oxime.

6-bromoindirubin-3'-oxime: structure in first source
purvalanol bpurvalanol B: protein kinase inhibitor; structure in first sourcepurvalanolprotein kinase inhibitor
purvalanol a6-((3-chloro)anilino)-2-(isopropyl-2-hydroxyethylamino)-9-isopropylpurine: purvalanol A is the (1R)-isomer;purvalanol
2-methyl-5-(4-methylanilino)-1,3-benzothiazole-4,7-dioneaminotoluene
cgp 60474substituted aniline
cgp 74514a
1,4-dimethoxy-10H-acridine-9-thioneacridines
bms 387032N-(5-(((5-(1,1-dimethylethyl)-2-oxazolyl)methyl)thio)-2-thiazolyl)-4-piperidinecarboxamide: a CDK2 inhibitor with antineoplastic activity; structure in first source

N-(5-{[(5-tert-butyl-1,3-oxazol-2-yl)methyl]sulfanyl}-1,3-thiazol-2-yl)piperidine-4-carboxamide : A secondary carboxamide resulting from the formal condensation of the carboxy group of piperidine-4-carboxylic acid with the amino group of 5-{[(5-tert-butyl-1,3-oxazol-2-yl)methyl]sulfanyl}-1,3-thiazol-2-amine. It is an ATP-competitive inhibitor of CDK2, CDK7 and CDK9 kinases and exhibits anti-cancer properties.
1,3-oxazoles;
1,3-thiazoles;
organic sulfide;
piperidinecarboxamide;
secondary carboxamide
angiogenesis inhibitor;
antineoplastic agent;
apoptosis inducer;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
7-butyl-6-(4-methoxyphenyl)-5H-pyrrolo[2,3-b]pyrazinepyrroles
alsterpaullonealsterpaullone : An organic heterotetracyclic compound that is 1,3-dihydro-2H-1-benzazepin-2-one which shares its 4-5 bond with the 3-2 bond of 5-nitro-1H-indole.

alsterpaullone: structure in first source
C-nitro compound;
caprolactams;
organic heterotetracyclic compound
anti-HIV-1 agent;
antineoplastic agent;
apoptosis inducer;
EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.11.26 (tau-protein kinase) inhibitor
quercetin7-hydroxyflavonol;
pentahydroxyflavone
antibacterial agent;
antineoplastic agent;
antioxidant;
Aurora kinase inhibitor;
chelator;
EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor;
geroprotector;
phytoestrogen;
plant metabolite;
protein kinase inhibitor;
radical scavenger
apigeninChamomile: Common name for several daisy-like plants (MATRICARIA; TRIPLEUROSPERMUM; ANTHEMIS; CHAMAEMELUM) native to Europe and Western Asia, now naturalized in the United States and Australia.trihydroxyflavoneantineoplastic agent;
metabolite
luteolin3'-hydroxyflavonoid;
tetrahydroxyflavone
angiogenesis inhibitor;
anti-inflammatory agent;
antineoplastic agent;
apoptosis inducer;
c-Jun N-terminal kinase inhibitor;
EC 2.3.1.85 (fatty acid synthase) inhibitor;
immunomodulator;
nephroprotective agent;
plant metabolite;
radical scavenger;
vascular endothelial growth factor receptor antagonist
kaempferol7-hydroxyflavonol;
flavonols;
tetrahydroxyflavone
antibacterial agent;
geroprotector;
human blood serum metabolite;
human urinary metabolite;
human xenobiotic metabolite;
plant metabolite
harmineharmine : A harmala alkaloid in which the harman skeleton is methoxy-substituted at C-7.

Harmine: Alkaloid isolated from seeds of PEGANUM HARMALA; ZYGOPHYLLACEAE. It is identical to banisterine, or telepathine, from Banisteria caapi and is one of the active ingredients of hallucinogenic drinks made in the western Amazon region from related plants. It has no therapeutic use, but (as banisterine) was hailed as a cure for postencephalitic PARKINSON DISEASE in the 1920's.
harmala alkaloidanti-HIV agent;
EC 1.4.3.4 (monoamine oxidase) inhibitor;
metabolite
aureusidinaureusidin : A hydroxyaurone that is aurone substituted by hydroxy groups at positions 4, 6, 3' and 4' respectively.

aureusidin: structure in first source
hydroxyauroneplant metabolite
sulfuretinsulfuretin: the chalcone C ring closes into a 5 instead of the more typical 6 membered ring leaving a phenyl methane at the 2 position instead of the typical phenyl1-benzofurans
chrysinchrysin : A dihydroxyflavone in which the two hydroxy groups are located at positions 5 and 7.7-hydroxyflavonol;
dihydroxyflavone
anti-inflammatory agent;
antineoplastic agent;
antioxidant;
EC 2.7.11.18 (myosin-light-chain kinase) inhibitor;
hepatoprotective agent;
plant metabolite
cupressuflavonecupressuflavone : A biflavonoid that is obtained by oxidative coupling of two molecules of apigenin resulting in a bond between positions C-8 of the two chromene rings respectively. Isolated from Cupressus sempervirens and Juniperus occidentalis, it exhibits free radical scavenging and antielastase activities.

cupressuflavone: from Cupressus macrocarpa; structure in first source
biflavonoid;
hydroxyflavone;
ring assembly
EC 3.4.21.37 (leukocyte elastase) inhibitor;
metabolite;
radical scavenger
fisetin3'-hydroxyflavonoid;
7-hydroxyflavonol;
tetrahydroxyflavone
anti-inflammatory agent;
antioxidant;
EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor;
geroprotector;
metabolite;
plant metabolite
demethylbellidifolinbellidin : A member of the class of xanthones that is xanthone which is substituted by hydroxy groups at positions 1, 3, 5, and 8. A natural product found particularly in Iris nigricans and Gentiana campestris.

demethylbellidifolin: protects the myocardium against damage due to ischemia-reperfusion in rats
tetrol;
xanthones
antioxidant;
EC 3.1.1.7 (acetylcholinesterase) inhibitor;
metabolite;
mutagen;
radical scavenger
hyperosidequercetin 3-O-beta-D-galactopyranoside : A quercetin O-glycoside that is quercetin with a beta-D-galactosyl residue attached at position 3. Isolated from Artemisia capillaris, it exhibits hepatoprotective activity.beta-D-galactoside;
monosaccharide derivative;
quercetin O-glycoside;
tetrahydroxyflavone
hepatoprotective agent;
plant metabolite
alvocidibalvocidib : A synthetic dihydroxyflavone that is 5,7-dihydroxyflavone which is substituted by a 3-hydroxy-1-methylpiperidin-4-yl group at position 8 and by a chlorine at the 2' position (the (-)-3S,4R stereoisomer). A cyclin-dependent kinase 9 (CDK9) inhibitor, it has been studied for the treatment of acute myeloid leukaemia, arthritis and atherosclerotic plaque formation.

alvocidib: structure given in first source
dihydroxyflavone;
hydroxypiperidine;
monochlorobenzenes;
tertiary amino compound
antineoplastic agent;
antirheumatic drug;
apoptosis inducer;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
aftin-4aftin-4: increases production of amyloid-beta protein (1-42)
su 9516
arcyriaflavin aarcyriaflavin A: from marine ascidian, Eudistoma sp.; structure given in first sourceindolocarbazole
palbociclibaminopyridine;
aromatic ketone;
cyclopentanes;
piperidines;
pyridopyrimidine;
secondary amino compound;
tertiary amino compound
antineoplastic agent;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
olomoucine iiolomoucine II: structure in first source
manzamine amanzamine A : An alkaloid of the class of beta-carbolines isolated from Haliclona and Acanthostrongylophora. It exhibits inhibitory activity against Glycogen Synthase Kinase-3 (EC 2.7.11.26).

manzamine A: RN given refers to (1R-(1R*,9Z,13S*,13aR*,20aR*,21aR*)-isomer; RN for cpd without isomeric designation not avail 12/92
alkaloid;
beta-carbolines;
isoquinolines
animal metabolite;
anti-HSV-1 agent;
antimalarial;
antineoplastic agent;
EC 2.7.11.26 (tau-protein kinase) inhibitor;
marine metabolite
1-azakenpaullone1-azakenpaullone : An organic heterotetracyclic compound that is 7,12-dihydropyrido[3',2':2,3]azepino[4,5-b]indole substituted at positions 6 and 9 by oxo and bromo groups respectively.lactam;
organic heterotetracyclic compound;
organobromine compound;
organonitrogen heterocyclic compound
EC 2.7.11.26 (tau-protein kinase) inhibitor;
Wnt signalling activator
cvt 313CVT 313: a potent inhibitor of CDK2 that prevents neointimal proliferation; structure given in first source
leucettamine bleucettamine B: a protein kinase inhibitor isolated from the marine sponge Leucetta microraphis; structure in first source
nu 61404-(6-cyclohexylmethoxy-9H-purin-2-ylamino)-N,N-diethylbenzamide: a cyclin-dependent kinase inhibitor; structure in first source
meridianin ameridianin A: structure in first source
rgb 286638
at 75194-(2,6-dichlorobenzamido)-N-(piperidin-4-yl)-pyrazole-3-carboxamide : A member of the class of pryrazoles that is 4-amino-1H-pyrazole-3-carboxylic acid in which the primary amino group has been acylated by a 2,6-dichlorobenzoyl group and in which the carboxylic acid has been converted into a carboxamide by formal condensation with the primary amino group of 4-aminopiperidine.dichlorobenzene;
piperidines;
pyrazoles;
secondary carboxamide
antineoplastic agent;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
pha 848125N,1,4,4-tetramethyl-8-((4-(4-methylpiperazin-1-yl)phenyl)amino)-4,5-dihydro-1H-pyrazolo(4,3-h)quinazoline-3-carboxamide: a cyclin dependent kinase inhibitor
14-methyl-20-oxa-5,7,14,26-tetraazatetracyclo(19.3.1.1(2,6).1(8,12))heptacosa-1(25),2(26),3,5,8(27),9,11,16,21,23-decaene14-methyl-20-oxa-5,7,14,26-tetraazatetracyclo(19.3.1.1(2,6).1(8,12))heptacosa-1(25),2(26),3,5,8(27),9,11,16,21,23-decaene: has antineoplastic activity; also inhibits Fms-like tyrosine kinase-3; structure in first source
meriolin 3meriolin 3: a cell death-inducing kinase inhibitor; structure in first source
amg 4581-(2-hydroxy-2-methylpropyl)-N-(5-(7-methoxyquinolin-4-yloxy)pyridin-2-yl)-5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxamide: a c-met inhibitor; structure in first source
cink4CINK4: cyclin-dependent kinase 4 inhibitor; may have tumor suppression activity; structure in first sourceindoles
ldc067
(R)-DRF053(R)-DRF053 : A member of the class of 2,6-diaminopurines that is 2,6-diamiopurine which is substituted by an isopropyl group at position 9 and in which the amino groups at positions 2 and 6 are substituted by a 1-hydroxybutan-2-yl and 3-(pyridin-2-yl)phenyl groups, respectively (the R enantiomer). A cyclin dependent kinase inhibitor, widely used as its hydrochloride hydrate.2,6-diaminopurines;
phenylpyridine;
primary alcohol;
secondary amino compound
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
ribociclibribociclib: inhibits both CDK4 and CDK6
bay 1000394roniciclib: an antineoplastic agent that inhibits cyclin-dependent kinases; structure in first source
pha 793887piperidinecarboxamide
abemaciclib
dinaciclibpyrazolopyrimidine
nms p937NMS P937: a polo-like kinase 1 inhibitor; structure in first source
bs-181BS-181: a CDK7 inhibitor with antineoplastic activitypyrazolopyrimidine
on123300ON123300: a protein kinase inhibitor; structure in first source
chr-6494
((5z)5-(1,3-benzodioxol-5-yl)methylene-2-phenylamino-3,5-dihydro-4h-imidazol-4-one)leucettine L41 : A member of the class of benzodioxoles that is 1,3-benzodioxole substituted by a (2-anilino-5-oxo-1,5-dihydro-4H-imidazol-4-ylidene)methyl group at position 5. It is an inhibitor of DYRK1A, DYRK2, CLK1, and CLK3 (IC50s = 0.04, 0.035, 0.015, and 4.5 muM, respectively).benzodioxoles;
imidazolone;
substituted aniline
autophagy inducer;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.12.1 (dual-specificity kinase) inhibitor;
neuroprotective agent;
nootropic agent
ro 3306RO 3306: structure in first source
hymenialdisine
7-bromoindirubin-3'-oxime7-bromoindirubin-3'-oxime: has mild protein kinase inhibitory activity; induces caspase-independent cell death; structure in first source
debromohymenialdisine