FIG. 2.

Kinetics of splicing and MB-mediated cross-linking. Results from a 3-h time course of splicing (A), MB cross-linking (B), and UV cross-linking (C) of GC+DX RNA are shown. Splicing was carried out with 60% HeLa nuclear extract for the times indicated. RNA was [³²P]UTP labeled to low specific activity for splicing and was [³²P]GTP labeled to high specific activity for cross-linking (see Materials and Methods). Lane M contains protein markers with sizes in kilodaltons indicated to the left of panel B. Note the ∼65-kDa band detected by MB but not UV cross-linking that appears transiently during the time course.