The U7 snRNP. This particle contains the U7 snRNA, the smallest of the snRNAs which varies from 57-70 nts long depending on the species. The 5’ end of U7 snRNA binds to a sequence 3’ of the stemloop, termed the histone downstream element (HDE). There are a number of proteins found in the U7 snRNP. There are 7 Sm proteins, as are present in the spliceosomal snRNP. Five of these proteins are the same as ones found in the spliceosomal snRNPs and there are 2, Lsm10 and Lsm11 that are unique to U7 snRNP. A third protein joins the U7 snRNP, ZFP100, a large zinc finger protein. ZFP100 interacts with SLBP bound to the histone pre-mRNA and with Lsm11 and likely plays a critical role in recruiting U7 snRNP to the histone pre-mRNA.