Multiple phosphorylation sites and quaternary organization of guanine-nucleotide exchange complex of elongation factor-1 (EF-1betagammadelta/ValRS) control the various functions of EF-1alpha.

The eukaryotic guanine-nucleotide exchange factor commonly called elongation factor-1 betagammadelta (EF-1betagammadelta), comprises four different subunits including valyl-tRNA synthetase (EF-1betagammadelta/ValRS). The factor is multiply-phosphorylated by three different protein kinases, protein kinase C, casein kinase II and cyclin dependent kinase 1 (CDKI). EF-1betagammadelta/ValRS is organized as a macromolecular complex for which we propose a new structural model. Evidence that EF-1betagammadelta/ValRS is a sophisticated supramolecular complex containing many phosphorylation sites, makes it a potential regulator of any of the functions of its partner EF-1alpha, not only involved in protein synthesis elongation, but also in many other cellular functions.