Lastly, a "toeprint" of 30S subunits bound to T4 gene 32 mRNA has been observed with MMLV reverse transcriptase; while the experiment has not been quantitated, appearance of a signal at a subunit concentration of 0.02 μM is consistent with a binding constant on the order of 10⁷ M⁻¹ (Hartz et al., 1991).
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