Module 2: Figure ROS microdomains
Localized ROS signalling in a microdomain surrounding the B cell receptor.
Under resting conditions, the protein phosphorylation cascade that operates between Lyn, Syk, Bruton's tyrosine kinase (Btk) and phospholipase C (PLC) (Module 2: Figure ROS effects on Ca2+ signalling) is inhibited by the tyrosine phosphatase Src homology 2 (SH2) domain-containing protein tyrosine phosphatase-1 (SHP-1), which is present at very high levels. When the receptor is stimulated by antigen, there is a Ca2+-dependent activation of dual oxidase (DUOX) that creates a microdomain of H2O2 (yellow oblong) to inhibit the SHP-1 enzymes in the immediate vicinity of the B cell receptor (BCR). This figure is based on information taken from Singh et al. 2005.