Fig. 1. Reverse-tagged protein baits of the Nug1-containing 60S pre- ribosome are associated with pre-ribosomal particles of different sizes. The sedimentation behavior of the indicated TAP-tagged proteins was analyzed on sucrose density gradients, and ribosomal fractions (40S, 60S, 80S and polysomes) were determined by OD₂₅₄ measurement of the gradient fractions (upper graph). Western blot analysis of these gradient fractions using anti-ProtA antibodies reveals the position of the indicated TAP-tagged baits (lower panel). Note that some baits (e.g. Nsa3) exhibit a broad distribution on the sucrose gradient, whereas other baits (e.g. Kre35) exhibit a distinct peak at ∼60S (see text).