Isolation and characterization of nuclear ribonucleoprotein complexes from Drosophila melanogaster

The isolation of total nuclear ribonucleoprotein particles from Drosophila melanogaster embryos, using a pH 8.0, 01 M NaCl extraction of purified nuclei, is described. When the extract is fractionated on isokinetic sucrose gradients, at least six major classes of nuclear ribonucleoprotein complexes, differing in RNA and protein content as well as sedimentation behavior, are observed. The two largest complexes are preribosomal complexes. The remaining four major classes of RNPs sediment at roughly 6S, 8S, 12S and 30S. A minor class at 17S is also observed. The 30S fraction is 200-250 A in width and appears to be analogous to the mammalian monoparticle. It is composed primarily of polypeptides at about 36 000 and 37 000 daltons, along with 1-2 kilobase RNA fragments. The 6S, 8S and 12S complexes contain a few discrete small nuclear RNAs from 80-600 bases in length, along with a small number of polypeptides, about 50 000, 52 000, 56 000 and 75 000 daltons. These novel complexes are of the order of a 100 A in width (60-120 A range).