Phospholipase A2 crotoxin basic subunit CBb - P0CG56 (PA2BB_CRODU)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P0CG56: 1
Heterodimer CA-CB: Crotoxin is a potent presynaptic neurotoxin that possesses phospholipase A2 (PLA2) activity and exerts a lethal action by blocking neuromuscular transmission. It consists of a non-covalent association of a basic and weakly toxic PLA2 subunit (CBa2, CBb, CBc, or CBd), with a small acidic, non-enzymatic and non-toxic subunit (CA1, CA2, CA3 or CA4). The complex acts by binding to a specific 48-kDa protein (R48) receptor located on presynaptic membranes, forming a transient ternary complex CA-CB-R48, followed by dissociation of the CA-CB complex and release of the CA subunit. At equilibrium, only the CB subunits remain associated with the specific crotoxin receptor. In addition to neurotoxicity, crotoxin has been found to exert myotoxicity, nephrotoxicity, and cardiovascular toxicity (PubMed:20109480). Moreover, anti-inflammatory, immunomodulatory, anti-tumor and analgesic effects of crotoxin have also been reported (PubMed:20109480). UniProt
Catalytic Activity
a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn-glycero-3-phosphocholine + a fatty acid + H+ UniProt
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Subunit Structure
Heterodimer of one of the acidic (CA1, CA2, CA3 or CA4) and one of the basic (CBa1, CBa2, CBb, CBc or CBd) subunits; non-covalently linked. The acidic subunit is non-toxic, without enzymatic activity and comprises 3 peptides that are cross-linked by 5 disulfide bridges. The basic subunit is toxic, has phospholipase A2 activity and is composed of a single chain. Multiple variants of each subunit give different crotoxin complexes that can be subdivided into 2 classes: (1) those of high toxicity, low PLA2 activity (CBb, CBc and CBd linked with high affinity to any CA) and high stability (K(d)=4.5 nM) and (2) those of moderate toxicity, high PLA2 activity (CBa2 linked with low affinity to any CA) and low stability (K(d)=25 nM). UniProt
  • Organism: South American rattlesnake
  • Length:
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