The conformational change also switches LysRS activity from aminoacylation of Lysine tRNA to diadenosine tetraphosphate (Ap4A) production. Ap4A, which is an adenosine joined to another adenosine through a 5‘-5’tetraphosphate bridge, binds to HINT1 and this releases MITF from the inhibitory complex, allowing it to transcribe its target genes. Specifically, Ap4A causes a polymerization of the HINT1 molecule into filaments.
The conformational change in LysRS activity shifts it from aminoacylation of lysine tRNA to the production of diadenosine tetraphosphate (Ap4A). Ap4A binds to HINT1, releasing MITF from its inhibitory complex, allowing it to transcribe target genes. This is because Ap4A causes a polymerization of HINT1 molecules into filaments.