Extended Data Fig. 1: Purification, electron microscopy and reverse transcriptase activity of human L1 ORF2p and mutants.

(a) Size exclusion chromatogram (top) and SDS-PAGE of the final step of L1 ORF2p purification stained with Coomassie dye (bottom). The experiment was replicated more than 10 independent times. (b) Cryo-electron micrograph of L1 ORF2p-RNP complex. The experiment was replicated more than 10 independent times. (c) Denaturing gel analysis of TPRT reaction products with M-MLV RT (negative control) and wild-type L1 ORF2p using AJh 25 A as the template RNA (141nt). The experiment was replicated 3 independent times. (d) Denaturing gel analysis of the amount of reverse transcribed product with RT template RNA (129 nt), base-paired at its 3′ end to a 9 nt primer, after 0, 1, 5 and 20 minutes by M-MLV RT, wild-type L1 ORF2p and L1 ORF2p mutants. RT mutant is RT-dead, and EN mutant is EN-dead. (e) Intensity of full-length cDNA product was quantified and plotted across time for all proteins. The experiment in (d) was replicated 3 independent times, cDNA product was normalized by the cDNA product generated by M-MLV RT at 5 min, and the mean and standard deviation across three repeats are plotted.