Biogenesis of the protein storage vacuole crystalloid

We identify new organelles associated with the vacuolar system in plant cel ls. These organelles are defined biochemically by their internal content of three integral membrane proteins: a chimeric reporter protein that moves t here directly from the ER; a specific tonoplast intrinsic protein; and a no vel receptor-like RING-H2 protein that traffics through the Golgi apparatus . Highly conserved homologues of the latter are expressed in animal cells. In a developmentally regulated manner, the organelles are taken up into vac uoles where, in seed protein storage vacuoles, they form a membrane-contain ing crystalloid, The uptake and preservation of the contents of these organ elles in vacuoles represents a unique mechanism for compartmentalization of protein and lipid for storage.