MAJOR INTRACELLULAR-LOCALIZATION OF ELONGATION FACTOR-I

Polyclonal antibodies directed against the two components of EF-1, the G-protein EF-1 alpha and the guanine-nucleotide exchange complex EF-1 beta gamma delta, were used for the analysis of EF-1. We show that Xe nopus oocytes as well as Xenopus A6 cultured cells contain comparable ratios around 2:1 of EF-1 alpha versus EF-1 beta gamma delta. Immunolo calization of EF-1 was analyzed in A6 cultured cells. Both components appeared to be mainly localized in the cytoplasmic compartment, as a g ranulous diffuse network forming a gradient from the nucleus to the pe riphery of the cells. The major fraction of EF-1 was correlated to end oplasmic reticulum localization and not to the microtubule network. Co -localization of EF-1 with the endoplasmic reticulum is consistent wit h the function of EF-1 in peptide chain elongation.