Skip Header

You are using a version of browser that may not display all the features of this website. Please consider upgrading your browser.

Alpha-amanitin proprotein

Amanita phalloides (Death cap)
Reviewed-Annotation score: -Experimental evidence at protein leveli


Major toxin belonging to the bicyclic octapeptides amatoxins that acts by binding non-competitively to RNA polymerase II and greatly slowing the elongation of transcripts from target promoters (PubMed:4865716, PubMed:363352, PubMed:7642577, PubMed:8702941).1 Publication4 Publications


The typical symptoms of amatoxin poisoning are gastro-intestinal distress beginning 6-12 h after ingestion, a remission phase lasting 12-24 h, and progressive loss of liver function culminating in death within 3-5 days (PubMed:12475187). One of the few effective treatments is liver transplantation (PubMed:12475187).1 Publication


This peptide is cyclic. The peptide order is assigned by homology with the gene sequence for alpha-amanitin from Amanita bisporigera.Curated
In peptide sequencing work prior to 1968, the residue shown in the first position was reported as a beta-methylleucine derivative that could arise by either beta-methylation of leucine or gamma-methylation of isoleucine. The correct structure has been determined to be derived from isoleucine without methylation.Curated

GO - Molecular functioni


Molecular functionToxin

Names & Taxonomyi

Protein namesi
Recommended name:
Alpha-amanitin proprotein1 Publication
Cleaved into the following chain:
Alpha-amanitin1 Publication
Alternative name(s):
Amatoxin1 Publication
Gamma-amanitin1 Publication
OrganismiAmanita phalloides (Death cap)
Taxonomic identifieri67723 [NCBI]
Taxonomic lineageiEukaryotaFungiDikaryaBasidiomycotaAgaricomycotinaAgaricomycetesAgaricomycetidaeAgaricalesAmanitaceaeAmanita

Pathology & Biotechi

Toxic dosei

LD50 is 0.35 mg/kg by intraperitoneal injection into mice (PubMed:363352). LD50 is 4 mg/kg by intravenous injection into rats, and 0.1 mg/kg by intravenous injection into dogs (PubMed:363352). LD50 is 2 µg/kg by intracerebroventricular injection into mice, and 10 µg/kg by intracerebroventricular injection into rats (PubMed:363352).1 Publication

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
PeptideiPRO_00003491371 – 8Alpha-amanitin2 Publications8
PropeptideiPRO_00004437199 – 23By similarityAdd BLAST15

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Cross-linki1 ↔ 8Cyclopeptide (Ile-Pro)3 Publications
Modified residuei1(3R,4R)-4,5-dihydroxyisoleucine; in form alpha-amanitin1 Publication1
Modified residuei1(3R,4S)-4-hydroxyisoleucine; in form gamma-amanitin1 Publication1
Cross-linki2 ↔ 62'-cysteinyl-6'-hydroxytryptophan sulfoxide (Trp-Cys)Curated
Modified residuei84-hydroxyproline3 Publications1

Post-translational modificationi

Processed by the macrocyclase-peptidase enzyme POPB to yield a toxic cyclic decapeptide (PubMed:24613547). POPB first removes 10 residues from the N-terminus (By similarity). Conformational trapping of the remaining peptide forces the enzyme to release this intermediate rather than proceed to macrocyclization (By similarity). The enzyme rebinds the remaining peptide in a different conformation and catalyzes macrocyclization of the N-terminal 8 residues (By similarity).By similarity1 Publication

Keywords - PTMi

Hydroxylation, Thioether bond


Protein-protein interaction databases

IntActiP85421, 12 interactors


Secondary structure

Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Turni4 – 6Combined sources3

3D structure databases


Miscellaneous databases


Family & Domainsi

Sequence similaritiesi

Belongs to the MSDIN fungal toxin family.Curated


Sequence statusi: Fragment.

Sequence processingi: The displayed sequence is further processed into a mature form.

P85421-1 [UniParc]FASTAAdd to basket

« Hide

        10         20 
Mass (Da):2,345
Last modified:March 28, 2018 - v2

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Non-terminal residuei1Curated1

Sequence databases

Select the link destinations:
Links Updated
KC778577 Genomic DNA Translation: AGO98233.1
KF546288 Genomic DNA Translation: AHX98312.1
KF546289 Genomic DNA Translation: AHX98313.1

Similar proteinsi

Entry informationi

Entry nameiAAMAT_AMAPH
AccessioniPrimary (citable) accession number: P85421
Secondary accession number(s): A0A023UBX2
Entry historyiIntegrated into UniProtKB/Swiss-Prot: September 2, 2008
Last sequence update: March 28, 2018
Last modified: July 18, 2018
This is version 24 of the entry and version 2 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programFungal Protein Annotation Program


Keywords - Technical termi

3D-structure, Direct protein sequencing


  1. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  2. SIMILARITY comments
    Index of protein domains and families

We'd like to inform you that we have updated our Privacy Notice to comply with Europe’s new General Data Protection Regulation (GDPR) that applies since 25 May 2018.

Do not show this banner again
UniProt is an ELIXIR core data resource
Main funding by: National Institutes of Health