9.B.437.1.1
GRA64 of 330 aas and 2 TMSs, N- and C-terminal. Part of T. gondii's success lies in its ability to infect diverse organisms and host cells and to persist as a latent infection within parasite-constructed structures called tissue cysts. Mayoral et al. 2022 characterized GRA64. On the vacuolar membrane, this protein is exposed to the host cell cytosol and interacts with host ESCRT proteins. Parasites lacking the GRA64 protein exhibit ultrastructural changes in tissue cysts during chronic infection (Mayoral et al. 2022).  LC3-dependent extracellular vesicle (EV) loading and secretion (LDELS) is a secretory autophagy pathway in which the macroautophagy/autophagy machinery facilitates the packaging of cytosolic cargos, such as RNA-binding proteins, into EVs for secretion outside of the cell. Gardner et al. 2023 identified TFRC (transferrin receptor), one of the first proteins found to be secreted via EVs, as a transmembrane cargo of the LDELS pathway. Similar to other LDELS targets, TFRC secretion via EVs genetically requires components of the MAP1LC3/LC3-conjugation machinery but is independent of other ATGs involved in classical autophagosome formation. The packaging and secretion of TFRC into EVs depends on multiple ESCRT pathway components and the small GTPase, RAB27A. It was suggested that the LDELS pathway promotes TFRC incorporation into EVs and its subsequent secretion outside the cell (Gardner et al. 2023).