Figure 2.

Analysis of human SRP68 on 10%–40% sucrose gradients. (A) SRP68 prepared in urea (black bars) or SLS (gray bars). (B) Comigration of SRP68 (prepared in SLS; gray bars), recombinant SRP72 (white bars), and human SRP RNA (solid line). Fractions are numbered from 2 to 16. Proteins and RNA in the various fractions were analyzed by gel electrophoresis followed by measuring the intensities of the stained bands. The positions of the molecular weight marker proteins Fibrinogen (FBG, 340 kDa), Bovine Serum Albumin (BSA, 78 kDa), and Lysozyme (LYZ, 16 kDa) are indicated. Other arrowheads show the mobilities of the free SRP68/72 heterodimer (68/72) and of purified SRP72 (72) that were analyzed in parallel. (C) Secondary structures diagrams of human SRP RNA (left) and the Δ35nwt mutant RNA (right) (Larsen and Zwieb 1991; Iakhiaeva et al. 2005). Helices are numbered from 2 to 8; letters denote helical sections. Indicated are the positions of the two hinges (Halic et al. 2004; Zwieb et al. 2005) as well as the regions corresponding to the small (Alu) and the large (S) domain. Residues are numbered in increments of 10.