Page 241 - The Manga Guide to Biochemistry

Many of the ribozymes that have been discovered or artificially created so far
are involved in building or cleaving RNA or DNA.

Cech discovered that part of RNA itself catalyzes the chemical reaction to
remove sections that are meaningless as protein blueprints (introns) and to join
the sections that are meaningful (exons). This is referred to as self-splicing* and
is fairly rare.

Usually, splicing involves an enzyme known as spliceosome, which is a
large complex made of RNA and proteins.

Splicing involves several hydroxyl groups (-OH) of RNA, such as the 2´-OH or
the 3´-OH.

Intron

2’-OH 3’-OH
attack! attack!

Exon

Eukaryotic mRNA splicing removes

the intron ( ) parts.

Hey, it made a loop!

The discovery of ribozymes caused RNA to be viewed as a multifaceted
molecule that does a variety of tasks, and RNA research advanced rapidly.

As the 21st century began, this research showed that RNA has other various
roles and that many different forms of RNA exist in cells. RNA research is truly
in full bloom now, and there are high expectations for future research.

* The genes of eukaryotes (like humans) are divided into several exons by non-coding base
sequences called introns. The introns must be removed from the mRNA before translation,
in a reaction known as splicing.

Molecular Biology and the Biochemistry of Nucleic Acids 227