Guanosine triphosphate - dependent autocatalytic phosphorylation of peptide initiation factor 2 from rat liver

If incubated with [γ-³²P]guanosine triphosphate, homogenous peptide initiation factor 2 from rat liver liberates the terminal phosphate from GTP and utilizes 25–40% of it for its own phosphorylation. This phosphorylation is apparently autocatalytic since it does not require any additional proteins. Only the γ-subunit of the factor becomes phosphorylated by an acid-labile bond and the reaction is significantly inhibited by initiator Met-tRNA_F.