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==Mechanism of pertussis toxin== | ==Mechanism of pertussis toxin== | ||
Pertussis toxin acts on target cells through its A protomer which contains the '''enzymatically active S1 subunit'''. <br /> | Pertussis toxin acts on target cells through its A protomer which contains the '''enzymatically active S1 subunit'''. <br /> | ||
This subunit catalyzes '''ADP-ribosylation''' of the ''α-subunit of trimeric G proteins'', which disturbs functions of the target cells and therefore lead to various biological effects. | This subunit catalyzes [http://en.wikipedia.org/wiki/ADP_ribosylation '''ADP-ribosylation'''] of the ''α-subunit of trimeric G proteins'', which disturbs functions of the target cells and therefore lead to various biological effects. | ||
In facts, substrates of PTX are regulators of the membrane-bound adenylate cyclase. These G proteins bind GTP in order to transduce signals in the cell. When ADP-ribosylation by PTX occurs, ''the downregulation of the adenylate cyclase activity is inhibited''. This inhibition leads to increase cAMP levels in cells, which explains the amount of biological activities of the toxin. | In facts, substrates of PTX are regulators of the membrane-bound adenylate cyclase. These G proteins bind GTP in order to transduce signals in the cell. When ADP-ribosylation by PTX occurs, ''the downregulation of the adenylate cyclase activity is inhibited''. This inhibition leads to increase cAMP levels in cells, which explains the amount of biological activities of the toxin. | ||