Messenger-clearing enzyme
Phosphodiesterase 3B (PDE3B)↓
Also searched as Phosphodiesterase 3B (PDE3B).
You want it quiet when you are trying to release fat. Insulin does not block the switch — it deletes the message: this enzyme hydrolyzes the second messenger so the kinase never activates. That is why fat release is suppressed after eating no matter what else is taken, and why every stimulus on this pathway is conditional on the fed state. It needs a partner protein to be stable, and without that partner insulin fails to suppress release at all — which shows how much of this depends on assembly rather than amount.
In depth
The enzyme insulin uses to destroy the fat-release signal before it can be read.
What drives it
Insulin sensitivity increases it.
'Insulin favors cAMP degradation through activation of protein kinase (PK) B and phosphodiesterase 3B (PDE-3B) activity' (Proc Nutr Soc). And assembly matters more than amount: 'stabilization of PDE3B, resulting from ABHD15 binding, is necessary for insulin-stimulated suppression of lipolysis in WAT. Upon loss of ABHD15, insulin fails to activate PDE3B-mediated cAMP degradation'. doi 10.3389/fphys.2022.826314
The Enabler increases it.
'stabilization of PDE3B, resulting from ABHD15 binding, is necessary for insulin-stimulated suppression of lipolysis in WAT. Upon loss of ABHD15, insulin fails to activate PDE3B-mediated cAMP degradation... Leading to unsuppressed lipolysis' (doi 10.3389/fphys.2022.826314). 'However, the precise molecular mechanism underlying the interaction between ABHD15 and PDE3B remains elusive.'. doi 10.3389/fphys.2022.826314
Bone-building receptor increases it.
The same receptor cancels itself. 'Gq signaling events lead to increased sequestration of cAMP by phosphodiesterase (pde) activation, which counteracts the lipolytic effects of Gs-coupled signaling elicited by PTHR1' (doi 10.1242/jeb.165381 [PMID 29514884]). The clearest single illustration of this MAP's recurring pattern — the limiter lives inside the accelerator. doi 10.1242/jeb.165381 · PMID 29514884
What it drives
It reduces The cell's go-signal.
How insulin actually works — it deletes the message. 'Insulin signaling activates phosphodiesterase 3B (PDE3B) through phosphorylation at Ser273 via the PKB... Activated PDE3B hydrolyzes cAMP to 5-AMP thereby reducing the cAMP levels and, therefore, PKA activity' (doi 10.3389/fphys.2022.826314). The source does not overstate it: 'several studies have challenged this and suggested that while PDE3B is essential under certain conditions, its function alone cannot fully explain the antilipolytic action.'. doi 10.3389/fphys.2022.826314
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.