Small Nuclear Ribonucleoprotein 25kDa (SNRNP25)

Two types of spliceosomes catalyze splicing of pre-mRNAs. The major U2-type spliceosome is found in all eukaryotes and removes U2-type introns, which represent more than 99% of pre-mRNA introns. The minor U12-type spliceosome is found in some eukaryotes and removes U12-type introns, which are rare and have distinct splice consensus signals. The U12-type spliceosome consists of several small nuclear RNAs and associated proteins. SNRNP25 encodes a 25K protein that is a component of the U12-type spliceosome.However, homologs of those associated with U11 were not detected in Drosophila melanogaster, consistent with the presence of a divergent U11 snRNP in flies.  The presence of unique U11/U12 snRNP proteins in the U12-type spliceosome provides insight into potential evolutionary relationships between the major and minor spliceosome.