sentence1: The Sm ring permanently binds to the snRNAs of U1 , U2 , U4 and U5 , which form four of the five snRNPs that form the main spliceosome .
sentence2: The Sm ring permanently binds to the snRNAs U1 , U2 , U4 and U5 , which form four of the five snRNPs that form the main spliceosome .