Transfer RNA tour

Source ^[1]

Structural highlights

Domains

Click here to color the tRNA 3D structure to match the secondary structure above.

The acceptor stem includes the 5' and 3' ends of the tRNA. The 5' end is generated by RNaseP :-). The 3' end is the site which is charged with amino acids for translation. Some aminoacyl tRNA synthetases interact with both the acceptor 3' end and

the anticodon when charging tRNAs. Note how far the 3' end is from the anticodon loop, at bottom, by clicking here. Note also how the acceptor stem stacks onto the TpsiC stem to form a continuous helix. The anticodon stem also stacks onto the junction between the variable loop and the D stem to form another nearly perfect helix. The TpsiC and D loops interact to bring the "cloverleaf" secondary structure in to the L-shaped tertiary structure.

The tour starts with the view. Now look at this .The backbone is yellow and the bases are magenta. Note that the major groove (at the top, when you have just clicked the button) is very deep.

Now change the display to make the show the connecting the phosphate atoms. Now the bases are easier to see. Notice how they are stacked upon each other but not perpendicular to the axis of the double helix. They are also displaced to the side of the axis. The result is a wide, short helix. Note also that the backbone forms a smooth, continuous curve.

You can .You are looking into the major groove and the colors of the base pairs alternate. You can also .

Each base pair stacks on the next similarly, as shown from . This is the . B-DNA stacks similarly, but compare this with Z-DNA, which behaves much differently. Essentially all helical RNA is in A form, but DNA can also be found in A form under certain conditions (particularly in RNA-DNA hybrids). The 2'-OH of ribose favors the C3'-endo sugar pucker necessary for A-form geometry. The O2' is easily seen as white spheres in .

You can compare it with the DNA forms by looking at this 3D red-blue stereo picture of A, B, and Z DNA