Fig. 8.

Model for the heterocyst-vegetative cell junction showing putative localization and interactions of FraC, FraD, and FraG. These proteins appear to be located in the plasma membrane and/or septum and involved in channel formation, either directly or by recruiting other factors. In a fully-developed heterocyst, FraG is found in the heterocyst neck around the cyanophycin, implicating FraG in an additional role to channel formation, possibly assembly or maintenance of heterocyst neck formation. C, Cyanophycin; CC, predicted Coiled Coil; L, predicted Linker domain; MD, Transmembrane domain; OM, Outer membrane; PG, Peptidoglycan; PM, Plasma membrane.