FIGURE 2.

Identification of abundant proteins in affinity-purified 37S exon and 45S B-like complexes. (A) Proteins were separated by 2D gel electrophoresis, stained with SPYRO Ruby, and the identities of protein spots were determined by mass spectrometry. Proteins smaller than 25 kDa were not analyzed. Abundant proteins and B-specific proteins only present in the 45S B-like complex are indicated in black and less abundant ones in gray. (B) Summary of abundant proteins detected by 2D gel electrophoresis in 37S exon and 45S B-like complexes. Abundant proteins in A were identified by visual inspection and are indicated by a gray box. Proteins are grouped according to their association with snRNPs or stage of recruitment. See the Supplemental Material for a detailed description as to why SRSF7, SRSF10, hPrp38, and Snu23 were also included in the group of abundant factors, despite less intensive staining, and hPrp19 and Smu-1 (in the 37S exon complex) were not considered to be abundant despite a staining intensity similar to, for example, hPrp31.