tokens: Using an RNase H protection assay and specific blocking oligonucleotides , we find that recognition of the 5 ' splice-site ( 5 ' ss ) and branchpoint sequence ( BPS ) elements by U11 and U12 snRNPs , respectively , displays strong cooperativity , requiring both sites in the pre mRNA substrate for efficient complex formation .
folded_tokens: use a rnase h protection assay and specific block oligonucleotide , we find that recognition of the 5 ' splice-site ( 5 ' ss ) and branchpoint sequence ( bp ) element by u11 and u12 snrnp , respectively , display strong cooperativity , require both site in the pre mrna substrate for efficient complex formation .