Splicing Factor 3B Subunit 5 (SF3B5)

Mass spectrometry was used to identify novel proteins associated with the human 17S U2 snRNP and one of its stable subunits, SF3b. Several additional proteins were identified, demonstrating that 17S U2 snRNPs are significantly more complex than previously thought. Two of the newly identified proteins, namely the DEAD-box proteins SF3b125 and hPrp5 were characterized further.

SF3b5 is a 10 kDa subunit of the splicing factor SF3b. SF3b associates with the splicing factor SF3a and a 12S RNA unit to form the U2 small nuclear ribonucleoproteins complex. SF3b5 and SF3b14b are also thought to facilitate the interaction of U2 with the branch site . Also included in this entry is RDS3 complex subunit 10, another protein involved in mRNA splicing.