T-independent response

Type 1 T-independent (TI-1) antigens bind to B cells through both Ig and innate immune receptors. LPS from Gram negative organisms binds to B cells via both mIg and TLR, resulting in signaling from both receptors. 

TLS Online TPP Program

#Id: 9071

#XL - T Zoology

Feedback mechanisms suppress signaling by the PKA pathway:

1. Intrinsic GTPase activity of Gαs

2. PDE acts to hydrolyze cAMP to 5′-AMP

3. By BARK

TLS Online TPP Program

#Id: 9072

#XL - T Zoology

In resting state 

basal level of PDE activity keeps cAMP levels below those necessary for PKA activation.

TLS Online TPP Program

#Id: 9073

#XL - T Zoology

TLS Online TPP Program

#Id: 9074

#XL - T Zoology

Activation of β-adrenergic receptors causes activation of C subunits of PKA which phosphorylate PDE, stimulating its catalytic activity.

TLS Online TPP Program

#Id: 9075

#XL - T Zoology

Active PDE hydrolyzes cAMP, driving cAMP levels back to basal levels.

TLS Online TPP Program

#Id: 9076

#XL - T Zoology

A G protein– coupled receptor kinase phosphorylates serine and threonine residues in the

cytoplasmic segments of activated GPCRs