Figure 4.

Involvement of PI3Kδ and lipid second messengers in B-cell-receptor signaling.

Notes: Activation of PI3Kδ upon stimulation of the B-cell receptor occurs via recruitment of p85 to a phosphotyrosine-docking site created by the Src-family kinase Lyn. PI3K activity leads to production of lipid second messengers and is counteracted by the phosphatases PTEN and SHIP. Red arrows indicate the activation of the kinases Akt and BTK by binding of lipid second messengers to their pleckstrin-homology domains that enables their localization at the plasma membrane. Further signaling events lead to regulation of transcription-factor activity.

Abbreviation: DAG, diacylglycerol.