Fig. 4.

Confirmation that intracellular E2-Crimson constructs were associated with the ER. The abbreviations for the constructs are as in Fig. 2. Projected confocal Z-stacks of the fluorescent proteins were merged with differential interference contrast images of the cells. a Htb2-GFP represents histone 2B tagged with GFP to label the nucleus. For the constructs with the α-factor signal sequence, much of the intracellular red fluorescence was in the nuclear envelope. For the construct with the Ost1 signal sequence, punctate aggregates were visible. b GFP-HDEL represents ER-targeted GFP with a C-terminal HDEL tetrapeptide for ER retention. For the constructs with the α-factor signal sequence, most of the GFP-HDEL remained in the cytosol. For the construct with the Ost1 signal sequence, GFP-HDEL exhibited a typical ER pattern, and was present in the same locations as the E2-Crimson aggregates. Scale bar, 2 μm