C1, see them all

Recent structural analysis of crystalline beta 2-chimaerin shows the central protein kinase C-like, diacyclglycerol (DAG)-binding C1 domain to be masked by its intramolecular interactions with the N-terminal SH2 and GAP domains, and linker regions. A mechanism of activation has been derived from modelling of a GAP-Rac GTPase complex - the auto-inhibitory constraints are released via membrane engagement, unmasking the C1 domain to enable DAG binding and subsequent GAP stimulation of Rac GTPase catalytic activity.