四 、 snrNP Particles snRNAs transcribed by rna pol ll complex with specific protein to form SnRNP. These rna are rich in uracil and are denoted as U1、U2etc U1、U2、U4、U5andU6 are those involved in pre-mRNA splicing. Many others seem to be involved in determining the sites of methylation of pre-rRNA and are located in the nucleolus.四、snRNP Particles snRNAs transcribed by RNA Pol II complex with specific protein to form snRNP. These RNA are rich in uracil and are denoted as U1、U2 etc. U1、U2、U4、U5 and U6 are those involved in pre-mRNA splicing. Many others seem to be involved in determining the sites of methylation of pre-rRNA and are located in the nulcleolus