Figure 2.

Sec61β interacts with microtubule. (A) COS-7 cells were harvested for microtubule co-sedimentation in the absence or presence of GTP/paclitaxel (G/P). Samples of the supernatant (S) and pellet (P) were analyzed by Western blotting. (B–D) As in (A), but transfected with full length Sec61β (B), Sec61β lacking residues 20–44 (C) or RFP-tagged Sec61β (D). The bands with asterisk (*) may be degraded RFP-Sec61β-HA. (E) Purified wild-type HA-cytSec61β was incubated with microtubules (MT) or not, for microtubule co-sedimentation. Samples were analyzed by Western blotting. (F) As in (E), but with HA-cytSec61β lacking residues 20–44. (G) Purified wild-type HA cytSec61β or HA-cytSec61β lacking residues 20–44 was incubated with tubulins and precipitated with anti-HA antibody. The levels of indicated proteins were analyzed with Western blotting