The U1 snRNP complex contains the U1 snRNA molecule and the U1 snRNP specific proteins U1-70K, U1A and U1C, plus a common set of eight proteins, called Sm proteins U1A and U1-70K contain RNA binding domains and interact with naked snRNA on their own.
The U1 small nuclear ribonucleoprotein particle (snRNP) has an important function in the early formation of the spliceosome, the multicomponent complex in which pre-mRNA splicing takes place. The binding of U1C to the U1snRNP particle is dependent on protein-protein interactions between U1C and U1-70K as well as U1C and the common Sm proteins.
