Affinity purification of RNA-protein complexes

Beads containing immobilised protein or RNA (50% slurry in Binding buffera) prepared as described in Section 4.3.1.1 or 4.3.1.2. Binding buffera 10 mM HEPES-KOH, pH 7.9 lOOmMKCl 

coli tRNA (100x 5 p.g/p.1 RNase free Boehringer Mannheim) Bovine serum albumin (50x 10 xg/pl) 

1 mM EDTA 50 ng/ xl E. coli tRNA Protein elution buffer 58 mM Tris-HCl, pH 6.8 6% glycerol 1.7% SDS 

0025% Serva Blue W 0.8% /3-mercaptoethanol RNA loading buffer 80% formamide, v/v 0.1% xylene cyanol 0.1% bromophenol blue 1 mM EDTA, pH 8.0 

1 50% slurry beads containing immobilised protein. 50-200 xl binding buffer containing 0.4 units/pi RNasin (Promega), 50 ng/pl E. coli tRNA, 0.2 pg/pl bovine serum albu- 

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