| Post Translational Modifications | Cleavage by granzyme A (GZMA) relieves autoinhibition by releasing the N-terminal moiety (Gasdermin-B, N-terminal) that initiates pyroptosis. Not cleaved by other granzymes. Major cleavage site takes places after Lys-244.a minor cleavage site takes place after Lys-229. Cleavage by neutrophil elastase ELANE, inhibits its ability to trigger pyroptosis. (Microbial infection) Ubiquitinated by S.flexneri IpaH7.8, leading to its degradation by the proteasome, thereby preventing its ability to form pores in bacterial-derived membranes. |
| Function | Gasdermin-B: Precursor of a pore-forming protein that acts as a downstream mediator of granzyme-mediated cell death. This form constitutes the precursor of the pore-forming protein: upon cleavage, the released N-terminal moiety (Gasdermin-B, N-terminal) binds to membranes and forms pores, triggering pyroptosis. Also acts as a regulator of epithelial cell repair independently of programmed cell death: translocates to the plasma membrane and promotes epithelial maintenance and repair by regulating PTK2/FAK-mediated phosphorylation of PDGFA. Gasdermin-B, N-terminal: Pore-forming protein produced by cleavage by granzyme A (GZMA), which causes membrane permeabilization and pyroptosis in target cells of cytotoxic T and natural killer (NK) cells. Key downstream mediator of granzyme-mediated cell death: (1) granzyme A (GZMA), delivered to target cells from cytotoxic T- and NK-cells, (2) specifically cleaves Gasdermin-B to generate this form. After cleavage, moves to the plasma membrane, homooligomerizes within the membrane and forms pores of 10-15 nanometers (nm) of inner diameter, triggering pyroptosis. The different isoforms recognize and bind different phospholipids on membranes, promoting cell death of different target cells. Isoform 4: Precursor of a pore-forming protein that acts as a downstream mediator of granzyme-mediated cell death and mediates pyroptosis. Following cleavage and activation by granzyme A (GZMA), the N-terminal part binds to membrane inner leaflet lipids, homooligomerizes within the human plasma membrane and forms pores of 10-15 nanometers (nm) of inner diameter, triggering pyroptosis. Recognizes and binds membrane inner leaflet lipids of human cells, such as phosphatidylinositol 4-phosphate, phosphatidylinositol 5-phosphate, bisphosphorylated phosphatidylinositols, such as phosphatidylinositol (4,5)-bisphosphate, and more weakly to phosphatidic acid. Also binds sufatide, a component of the apical membrane of epithelial cells. Isoform 6: Precursor of a pore-forming protein that acts as a downstream mediator of granzyme-mediated cell death and mediates pyroptosis of human cells. Following cleavage and activation by granzyme A (GZMA), the N-terminal part binds to membrane inner leaflet lipids, homooligomerizes within the human plasma membrane and forms pores of 10-15 nanometers (nm) of inner diameter, triggering pyroptosis. Isoform 1: Precursor of a pore-forming protein that acts as a downstream mediator of granzyme-mediated cell death and specifically mediates cell death of Gram-negative bacteria in response to infection. Following cleavage and activation by granzyme A (GZMA), the N-terminal part recognizes and binds phospholipids found on Gram-negative bacterial membranes, such as lipid A and cariolipin, homooligomerizes within the bacterial membranes and forms pores, triggering pyroptosis followed by cell death. In contrast to isoform 4, does not bind to membrane inner leaflet lipids of host human cell, such as phosphatidylinositol 4-phosphate, phosphatidylinositol 5-phosphate, bisphosphorylated phosphatidylinositols, such as phosphatidylinositol (4,5)-bisphosphate. Isoform 2: Not able to trigger pyroptosis. Isoform 3: Not able to trigger pyroptosis. |
