In the preceding papers, we showed that one of the two complementar factors of polypeptide chain elongation factor 1 (EF-1) from pig liver, EF-1α, functionally corresponds to bacterial EF-Tu (Nagata, S., Iwasaki, K., and Kaziro, Y. (1976)
Arch. Biochem. Biophys. 172, 168), while the other, EF-1βγ, as well as one of its subunits, EF-1β, corresponds to bacterial EF-Ts (Motoyoshi, K. and Iwasaki, K. (1977)
J. Biochem. 82, 703). Therefore, the interaction between EF-1α and EF-1β, corresponds to bacterial EF-Ts (Motoyoshi, K. and Iwasaki, K. (1977)
J. Biochem. 82, 703). Therefore, the interaction between EF-1α and EF-1βγ or EF-1β was examined and the following results were obtained. i) EF-1βγ catalytically promoted the exchange of [
14C]GDP bound to EF-1α with exogenous [
3H] GDP. ii) In the absence of the exogenous guanine nucleotide, EF-1βγ as well as β could displace GDP bound to EF-1αto form an EF-1α•EF-1βγ as well as an EF-1α•EF-1β complex. iii) The occurrence of α•EF-1βγ and EF-1α•EF-1β complexes was demonstrated by gel filtration on Sephadex G-150. These results strongly indicate that the mechanism of the action of EF-1βγ or EF-1β in converting EF-1α•GDP into EF-1α•GTP is analogous to bacterial EF-Ts, and the reaction is accomplished by the following reactions;
EF-1α•GDP+FE-1βγ(or EF-1β)_??_EF-1α•EF-1βγ(or EF-1β)+GDP
EF-1α•EF-1βγ(OR EF-1β)+GTP_??_EF-1α•GTP+EF-1βγ(or EF-1β).
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