when in vitro processing reactions containing either human histone h3 or mouse histone h3 transcripts are treated with rnase t1 and probed with antibodies specific for the sm protein determinants or for the trimethylguanosine cap structure unique to the u rnas present in small nuclear ribonucleoproteins , rna fragments that encompass the site of 3 ' end formation on the pre-mrna transcript are selectively recovered .
C0086418
human
C0019647
histone h3