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. Author manuscript; available in PMC: 2007 Dec 20.
Published in final edited form as: Mol Cell. 2007 Oct 26;28(2):240–252. doi: 10.1016/j.molcel.2007.09.026

Figure 6. Intact U2 snRNP Associates with Histone Pre-mRNAs In Vivo.

Figure 6

(A) A labeled U7-snRNP substrate containing the H2a 101-nt RNA element was microinjected into Xenopus GVs and incubated for 1 hr. After UV-irradiation, extracts were prepared and immunoprecipitated with α-hPrp43 or α-SF3b155 antibodies; α-IBP160 antibody served as a control. Pre-mRNA (Pre) enrichment of ~2-fold over processed product (Pro) was observed in the α-hPrp43 and α-SF3b155 precipitations in two separate experiments.

(B) Western blots with the indicated antibodies were performed on GV extract and HeLa nuclear extract, separated by SDS-PAGE.

(C) Immunoprecipitations using various α-U2 snRNP antibodies and α-IBP160 as a control were performed on extracts prepared with (+) or without (−) prior formaldehyde fixation of the HeLa cells. Histone mRNAs and RPL15 mRNA were detected via RT-PCR. The snRNAs, 7SK, and mgU2-25/61 scaRNA were detected by Northern blotting.