Ribonuclease Activity and Cytotoxicity
The ribonuclease activity of ECP is not essential for cytotoxicity.
When the two known ribonuclease active-site residues are modified to non-functional counterparts (Lysine at position 38 to Arginine and Histidine at position 128 to Aspartate) and compared to the wild-type ECP, the mutated ECP retains its cytotoxicity but no longer has its ribonuclease activity. The experiment confirmed that converting the two amino acids to non-functional counter parts did inhibit ECP’s ribonuclease activity. However, ECP retained it anti-parasitic activity. Also, it did not change the production and transportation of ECP in bacteria.
ECP is a potent cytotoxic protein capable of killing cells of guinea pig tracheal epithelium, mammalian leukemia, epidermis carcinoma, and breast carcinoma, as well as non-mammalian cells such as parasites, bacteria, and viruses.
Mature ECP is cytotoxic to human bronchial epithelial (BEAS-2B) cells by specific binding to cell surface heparan sulfate proteoglycans (HSPGs) followed by endocytosis.
Read more about this topic: Eosinophil Cationic Protein
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