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13. Beskrive strukturen og funktionen af et spliceosom
Stryer, s. 800-803, tab. 28.3, fig. 28-31

Spliceosome – a large, dynamic assembly composed of:

• snRNPs – small nuclear ribonucleoprotein particles, also called *snurps*. They are made of snRNA (small nuclear RNAs) associated with specific proteins. The snRNAs is transcribed by RNA polymerase II. The snRNAs involved in the spliceosome are: U1, U2, U4, U5, and U6.
   

• proteins called splicing factors
   

• mRNA precursor being processed  

The spliceosome has a vital role in splicing process.

U1 binds to the 5’-splice site and U2 binds to the branch point. A preformed U4-U5-U6 complex then joins the assembly to form the complete spliceosome.

U2 and U6 form the catalytic center of the spliceosome. 

The spliceosome uses ATP energy to carry out the accurate removal of the intron.

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