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. 2016 Dec;22(12):1844–1858. doi: 10.1261/rna.056523.116

FIGURE 1.

FIGURE 1.

The 7SK RNA and its 5′-terminal hairpin HPI. (A) Schematic representation of the 7SK RNP complex. P-TEFb comprises the cyclin T1 and the cyclin-dependent kinase CDK9. (B) Sequences and secondary structures of (i) the 7SK 5′-terminal hairpin (HPI-wt), (ii) HPI, and (iii) the three subdomain constructs (HPI-a, HPI-b, and HPI-c) used for nuclear magnetic resonance (NMR) studies. Outlined nucleotides at 5′-end were changed to improve transcription efficiency. The 11-nt apical loop of HPI-wt was substituted by a thermo-stable UUCG tetraloop (HPI). The RNA oligonucleotides HPI-a, HPI-b, and HPI-c comprise nucleotides 35–74, 29–38/69–82, and 24–36/73–87, respectively. Both HPI-a and HPI-b contain two additional G-C base pairs. The internal loop IL1 comprises (34/75–77) nucleotides. The bulges B1, B2, and B3 comprise (71/72), (40/41), and (63) residues, respectively. The M1 motif (green) contains the helix H2, the internal loop IL1, and the bulge B1. The M2 motif (blue) comprises the helix H3 and bulges B2 and B3.