Sandbox Reserved 818: Difference between revisions

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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 leads 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 leads to various biological effects.


In facts, substrates of PTX are regulators of the membrane-bound [http://en.wikipedia.org/wiki/Adenylate_cyclase 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 [http://en.wikipedia.org/wiki/Cyclic_adenosine_monophosphate 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 [http://en.wikipedia.org/wiki/Adenylate_cyclase adenylate cyclase]. When ADP-ribosylation by PTX occurs, ''the downregulation of the adenylate cyclase activity is inhibited''. This inhibition leads to increase [http://en.wikipedia.org/wiki/Cyclic_adenosine_monophosphate cAMP] levels in cells, which explains the amount of biological activities of the toxin.


The ADP-ribosylation of trimeric G proteins occurs on a '''cysteine residue''' in the ''C-terminal part of the α-subunit''
The ADP-ribosylation of trimeric G proteins occurs on a '''cysteine residue''' in the ''C-terminal part of the α-subunit''