The low-molecular-weight form of
elongation factor 1 (EF-1L) of the
cysts of the brine shrimp Artemia salina and [3H]phenylalanyl-
tRNA are able to form a stable complex which can be isolated on a Sephacryl S200 column. The formation of this complex is inhibited by increasing concentrations of
magnesium acetate and KCl. Furthermore, the formation of this complex is independent of the presence of
guanine nucleotides. Complex formation between EF-1L and phenylalanyl-
tRNA appears to be specific, since acylation of the
tRNA is a necessity for this interaction. Although EF-1L alone binds
GDP somewhat more strongly than
GTP, the complex between EF-1L and phenylalanyl-
tRNA binds
GTP exclusively. Our results support the idea that complex formation between EF-1L and aminoacyl-
tRNA precedes the enzymatic binding of aminoacyl-
tRNA to the 80-S ribosome. Subsequently to this binding, release of EF-1L from the ribosome occurs.