Extended Data Fig. 5: Impact of disruptive Lgl mutations on tripartite complex behaviours.

Explanation of the behaviours and properties of four disruptive Lgl mutations described in the text, referring to the overall model presented in Fig. 5. The IE > NE mutant in the PBM bypasses the plugged state of the complex, leading to rapid phosphorylation progression and complex dissolution. The LSR > ASA mutant of the high-affinity kinase docking motif is less stably tethered to the kinase domain as the wild-type protein, resulting in more rapid release combined with less efficient N-terminal Ser phosphorylation, while C-terminal phosphorylation is unaffected. The RPYSR mutant displays a decreased kinase domain interaction and is unable to correctly position the kinase domain for efficient phospho-transfer, resulting in an overall suppression of phosphorylation. The SSS > AAA non-phosphorylatable mutant is trapped in the capture state as it cannot be phosphorylated to form the initial product state required to assemble the plug. It behaves similar to the WT protein in overexpressed conditions, which is trapped in the plugged state, as it likely saturates the endogenous release mechanism impeding the progression of the reaction.