How Does Prime editing (pegRNA + RT + nCas9) Work?

Prime editing is like giving a book a little fix using special tools and instructions.

Imagine you have a favorite storybook, but there's one tiny mistake in it, maybe "The cat sat on the mat" is written as "The cat sat on the fat." You want to change that "fat" back to "mat," but you don't want to rewrite the whole book. That's where prime editing comes in.

Prime editing uses three main helpers:

• A pegRNA, which is like a smart instruction manual telling the editor exactly what letter to change and where.
• An RT, short for reverse transcriptase, which acts like a tiny typewriter that writes the new letter into the book.
• A nCas9, which works like a pair of scissors cutting out just the wrong part so it can be replaced.

The pegRNA shows the RT where to go and what to write. The nCas9 makes a small cut near the mistake in the book, letting the RT slip in the correct letter. It's like having a helper who knows exactly what to change, without messing up the rest of the story.

This way, you can fix just one letter, or even add a few new ones, with no extra pieces, like glue or tape.