Step I grrr Pertussis Toxin A Subunit

[phllystyl]

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What does it do?

Conflicting sources:

Baby Robbins - Functions like Cholera Toxin (ie inc Gs activity)
Micro made simple - inc Gs activity

however:

First aid - inhibits Gi
and
PubMed reveals tons of papers saying it inhibits Gi

wtf

 

[DarksideAllstar]

I thought that it increases cAMP, subsequently causing lymphocytosis with impaired chemotaxis of PMNs (due to extracellular cAMP), histamine senstization, and insulin synthesis.

 

[Pacifica]

According to my micro prof. (who writes board questions), it inactivates Gi, which causes elevated cAMP levels etc etc.
Hope this helps!

 

[phllystyl]

I thought that it increases cAMP, subsequently causing lymphocytosis with impaired chemotaxis of PMNs (due to extracellular cAMP), histamine senstization, and insulin synthesis.

yeah but both Gi inhibition and Gs activation can increase cAMP.

The extracellular Adenylyl Cyclase is different that Pertussis toxin.

 

[phllystyl]

According to my micro prof. (who writes board questions), it inactivates Gi, which causes elevated cAMP levels etc etc.
Hope this helps!

thanks!... one more vote for Gi! Shoulda brought my Jawetz with me today :/

 

[NebelDO]

definitly inhibits the Gi..which will increase cAMP

 

[BrooklynDO]

one more vote for dec Gi to inc cAMP

 

[lattimer13]

after studying for my biochem final i will also agree it that it inhibits Gi via ADP ribosylation of alpha-i subunit... so cAMP cannot be degraded


on the other hand, cholera toxin increases cAMP as well but by ADP ribosylating the alpha-s subunit so it is permanently active.