It is shown that Mg-protoporphyrin monomethyl ester as well as immediate chlorophyll precursors are localized in chloroplast submembrane particles, some of them being especially enriched. A conclusion is made that the centers of chlorophyll biosynthesis coupled with chloroplast submembrane particles perform a wide range of biosynthetic reactions beginning at least with Mg-protoporphyrin IX monomethyl ester transformation.