Figure 5.

Microtubule dynamics during MTOC repositioning. (A) Time-lapse images of a Jurkat–Raji conjugate (transmitted image) in which the Jurkat has been labeled with 3×GFP-EMTB to mark microtubules and RFP-Pericentrin to mark the MTOC (which appears yellow) (fluorescent images). Zoomed images of the boxed regions in the fluorescent images are shown underneath. The white arrows point to the straightening microtubules, and the yellow arrowheads point to the center of the IS where these microtubules abut. (B) As in A, but including a kymograph demonstrating the shortening of the straight microtubule stalk. (C) As in A, except the Jurkat has been labeled with 3×GFP-EMTB to mark microtubules and RFP-Farnesyl to mark the plasma membrane. The position of the MTOC, as inferred from the 3×GFP-EMTB signal, is marked with a white arrow. Yellow arrowheads point to the center of the IS contacted by the straight, shortening microtubule stalk. See also Video 5. (D) A split version of the 45-s image in C showing the colocalization (see arrows) between the tip of the straight, shortening microtubule stalk (green) and an invagination of the Jurkat’s plasma membrane (red) at the IS center. (E) As in A, except the Jurkat has been labeled with 3×GFP-EMTB and the Raji cell’s plasma membrane has been labeled with the membrane dye Cellvue Claret-Far Red. The yellow arrowheads mark the “nipple-like” protrusion of the Raji cell’s plasma membrane exactly across from where the microtubule stalk in the Jurkat cell abuts the IS. Bars: (A, C, and D) 5 µm; (B) 1 µm.