Role of Phospholipids in the Multiple Forms of Mammalian Elongation Factor 1

Evidence is presented that high-molecular-weight aggregates of elongation factor 1 from calf brain and liver contain phospholipids. Sucrose gradient analysis has shown that these high-molecular-weight species can be converted to a low-molecular-weight form after incubation with different phospholipase preparations. In addition, a partially purified elongation factor 1 from rabbit reticulocytes is also converted to a low-molecular-weight species by phospholipase treatment. These data indicate that phospholipids are involved in maintaining the integrity of the high-molecular-weight species and support the view that this species is an aggregate of the low-molecular-weight elongation factor 1.