Fig. 3.

Assembly of the pyrenoid. The Rubisco-binding motif (RbM) mediates the formation of three regions of the pyrenoid. The RbM-bearing protein EPYC1 binds to multiple Rubisco holoenzymes and creates a Rubisco–EPYC1 condensate that forms the pyrenoid matrix. The interaction of RbM-bearing thylakoid-anchored proteins RBMP1 and RBMP2 with Rubisco tethers the pyrenoid matrix to the tubule network. The starch sheath is moulded around the pyrenoid matrix through the action of SAGA1 and SAGA2, which bind to Rubisco through their RbM domain and bind to the starch sheath through their starch-binding domain.