The shows proteins in white and the three snRNAs in colour (U4: orange, U5: red, and U6: purple).
Focusing reveals secondary structure and extensive base pairing between the U4 and U6 snRNAs.
The spliceosome is assembled from the U4/U6.U5 tri-snRNP, the U1 snRNP, and the U2 snRNP. The U2 snRNP interacts with the region highlighted in blue . The U1 snRNP interacts with the U2 snRNP. The initial assembly is inactive; extensive conformational changes (including unwinding of the U4/U6 base pairing) are required for activation of the spliceosome.
For the source article see Nguyen et al, 2016[1].
