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Record Information
Version2.0
Creation Date2009-07-03 22:19:00 UTC
Update Date2014-12-24 20:25:37 UTC
Accession NumberT3D2498
Identification
Common NameGrammotoxin
ClassProtein
DescriptionGrammotoxin is a peptide toxin produced by the Chilean rose tarantula (Grammostola rosea). It inhibits voltage-gated calcium channels in neurons. (1)
Compound Type
  • Amide
  • Amine
  • Animal Toxin
  • Natural Compound
  • Organic Compound
  • Protein
  • Spider Toxin
Protein StructureT3d2498
Synonyms
Synonym
GMTX
Omega-grammotoxin SIA
Chemical FormulaNot Available
Average Molecular Mass9600.980 g/mol
CAS Registry Number152617-90-8
SequenceNot Available
Chemical Taxonomy
DescriptionNot Available
KingdomOrganic Compounds
Super ClassOrganic Acids
ClassCarboxylic Acids and Derivatives
Sub ClassAmino Acids, Peptides, and Analogues
Direct ParentPeptides
Alternative ParentsNot Available
SubstituentsNot Available
Molecular FrameworkNot Available
External DescriptorsNot Available
Biological Properties
StatusDetected and Not Quantified
OriginExogenous
Cellular LocationsNot Available
Biofluid LocationsNot Available
Tissue LocationsNot Available
PathwaysNot Available
ApplicationsNot Available
Biological RolesNot Available
Chemical RolesNot Available
Physical Properties
StateLiquid
AppearanceClear solution.
Experimental Properties
PropertyValue
Melting PointNot Available
Boiling PointNot Available
Solubility>10 mg/mL
LogPNot Available
Predicted PropertiesNot Available
Spectra
Spectra
Spectrum TypeDescriptionSplash KeyView
Toxicity Profile
Route of ExposureInjection (sting/bite) (2)
Mechanism of ToxicityGrammotoxin inhibits P-, Q- and N-type voltage-gated calcium channels in neurons. Binding to the calcium channels modifies their voltage-dependent gating. This makes it more difficult for channels to be opened by depolarization, so much larger depolarisations are required for channel activation. Grammotoxin also binds to potassium channels, but with lower affinity than to the calcium channels. (1)
MetabolismFree toxin may be removed by opsonization via the reticuloendothelial system (primarily the liver and kidneys) or it may be degraded through cellular internalization via the lysosomes. Lysosomes are membrane-enclosed organelles that contain an array of digestive enzymes, including several proteases.
Toxicity ValuesNot Available
Lethal DoseNot Available
Carcinogenicity (IARC Classification)No indication of carcinogenicity to humans (not listed by IARC).
Uses/SourcesGrammotoxin is a peptide toxin produced by the Chilean rose tarantula (Grammostola rosea). (1)
Minimum Risk LevelNot Available
Health EffectsGrammotoxin is neurotoxic. (1)
SymptomsTarantula bites can be very painful. In some individuals they may cause an allergic reaction, which is usually anaphylactic and will have symptoms such as breathing difficulties or chest pain. (3)
TreatmentNot Available
Normal Concentrations
Not Available
Abnormal Concentrations
Not Available
DrugBank IDNot Available
HMDB IDNot Available
PubChem Compound IDNot Available
ChEMBL IDNot Available
ChemSpider IDNot Available
KEGG IDNot Available
UniProt IDP60590
OMIM ID
ChEBI IDNot Available
BioCyc IDNot Available
CTD IDNot Available
Stitch IDNot Available
PDB ID1KOZ
ACToR IDNot Available
Wikipedia LinkNot Available
References
Synthesis ReferenceNot Available
MSDSNot Available
General References
  1. Wikipedia. Grammotoxin. Last Updated 28 April 2009. [Link]
  2. Wikipedia. Spider toxin. Last Updated 9 January 2009. [Link]
  3. Wikipedia. Tarantula. Last Updated 8 August 2009. [Link]
Gene Regulation
Up-Regulated GenesNot Available
Down-Regulated GenesNot Available

Targets

General Function:
Ubiquitin-like protein binding
Specific Function:
Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes, primarily in the brain, but also in the pancreas and cardiovascular system. Contributes to the regulation of the action potential (AP) repolarization, duration and frequency of repetitive AP firing in neurons, muscle cells and endocrine cells and plays a role in homeostatic attenuation of electrical excitability throughout the brain (PubMed:23161216). Plays also a role in the regulation of exocytosis independently of its electrical function (By similarity). Forms tetrameric potassium-selective channels through which potassium ions pass in accordance with their electrochemical gradient. The channel alternates between opened and closed conformations in response to the voltage difference across the membrane. Homotetrameric channels mediate a delayed-rectifier voltage-dependent outward potassium current that display rapid activation and slow inactivation in response to membrane depolarization (PubMed:8081723, PubMed:1283219, PubMed:10484328, PubMed:12560340, PubMed:19074135, PubMed:19717558, PubMed:24901643). Can form functional homotetrameric and heterotetrameric channels that contain variable proportions of KCNB2; channel properties depend on the type of alpha subunits that are part of the channel (By similarity). Can also form functional heterotetrameric channels with other alpha subunits that are non-conducting when expressed alone, such as KCNF1, KCNG1, KCNG3, KCNG4, KCNH1, KCNH2, KCNS1, KCNS2, KCNS3 and KCNV1, creating a functionally diverse range of channel complexes (PubMed:10484328, PubMed:11852086, PubMed:12060745, PubMed:19074135, PubMed:19717558, PubMed:24901643). Heterotetrameric channel activity formed with KCNS3 show increased current amplitude with the threshold for action potential activation shifted towards more negative values in hypoxic-treated pulmonary artery smooth muscle cells (By similarity). Channel properties are also modulated by cytoplasmic ancillary beta subunits such as AMIGO1, KCNE1, KCNE2 and KCNE3, slowing activation and inactivation rate of the delayed rectifier potassium channels (By similarity). In vivo, membranes probably contain a mixture of heteromeric potassium channel complexes, making it difficult to assign currents observed in intact tissues to any particular potassium channel family member. Major contributor to the slowly inactivating delayed-rectifier voltage-gated potassium current in neurons of the central nervous system, sympathetic ganglion neurons, neuroendocrine cells, pancreatic beta cells, cardiomyocytes and smooth muscle cells. Mediates the major part of the somatodendritic delayed-rectifier potassium current in hippocampal and cortical pyramidal neurons and sympathetic superior cervical ganglion (CGC) neurons that acts to slow down periods of firing, especially during high frequency stimulation. Plays a role in the induction of long-term potentiation (LTP) of neuron excitability in the CA3 layer of the hippocampus (By similarity). Contributes to the regulation of glucose-induced action potential amplitude and duration in pancreatic beta cells, hence limiting calcium influx and insulin secretion (PubMed:23161216). Plays a role in the regulation of resting membrane potential and contraction in hypoxia-treated pulmonary artery smooth muscle cells. May contribute to the regulation of the duration of both the action potential of cardiomyocytes and the heart ventricular repolarization QT interval. Contributes to the pronounced pro-apoptotic potassium current surge during neuronal apoptotic cell death in response to oxidative injury. May confer neuroprotection in response to hypoxia/ischemic insults by suppressing pyramidal neurons hyperexcitability in hippocampal and cortical regions (By similarity). Promotes trafficking of KCNG3, KCNH1 and KCNH2 to the cell surface membrane, presumably by forming heterotetrameric channels with these subunits (PubMed:12060745). Plays a role in the calcium-dependent recruitment and release of fusion-competent vesicles from the soma of neurons, neuroendocrine and glucose-induced pancreatic beta cells by binding key components of the fusion machinery in a pore-independent manner (By similarity).
Gene Name:
KCNB1
Uniprot ID:
Q14721
Molecular Weight:
95876.615 Da
References
  1. Wikipedia. Grammotoxin. Last Updated 28 April 2009. [Link]
General Function:
Voltage-gated calcium channel activity
Specific Function:
Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1B gives rise to N-type calcium currents. N-type calcium channels belong to the 'high-voltage activated' (HVA) group and are blocked by omega-conotoxin-GVIA (omega-CTx-GVIA) and by omega-agatoxin-IIIA (omega-Aga-IIIA). They are however insensitive to dihydropyridines (DHP), and omega-agatoxin-IVA (omega-Aga-IVA). Calcium channels containing alpha-1B subunit may play a role in directed migration of immature neurons.
Gene Name:
CACNA1B
Uniprot ID:
Q00975
Molecular Weight:
262493.84 Da
References
  1. Wikipedia. Grammotoxin. Last Updated 28 April 2009. [Link]
General Function:
Voltage-gated calcium channel activity
Specific Function:
Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1A gives rise to P and/or Q-type calcium currents. P/Q-type calcium channels belong to the 'high-voltage activated' (HVA) group and are blocked by the funnel toxin (Ftx) and by the omega-agatoxin-IVA (omega-Aga-IVA). They are however insensitive to dihydropyridines (DHP), and omega-conotoxin-GVIA (omega-CTx-GVIA).
Gene Name:
CACNA1A
Uniprot ID:
O00555
Molecular Weight:
282362.39 Da
References
  1. Wikipedia. Grammotoxin. Last Updated 28 April 2009. [Link]