Fig. 1. Effect of exogenous 4.1R expression on interphase tubulin and actin cytoskeletons in COS-7 cells. (A) Schematic representation of the exon map for the 4.1R protein (top) and the cDNA constructs used in the transfection experiments shown in B,C (bottom). Exons are coded as follows: striped, alternative; white, constitutive; black, noncoding. The number of each exon is shown at the bottom of the most upstream scheme. Three translation-initiation sites at exons 2' (ATG-1), 4 (ATG-2) and 8 (ATG-3) are indicated, as is the stop codon (TGA) at exon 21. (B) Conventional fluorescence micrographs showing COS-7 cells transfected with the indicated 4.1R-encoding cDNAs and subjected to double-immunofluorescence analysis with anti-tag 9E10 (left), and anti-tubulin YL1/2 (right) antibodies. (C) Cells were transfected with 4.1R⁶⁰16,18-encoding cDNA and triple stained with anti-tag 9E10 (top) and anti-tubulin YL1/2 (middle) antibodies, and with Alexa-Fluor-594/phalloidin (bottom). Projections of complete x-y optical section stacks were acquired by confocal microscopy. Arrows indicate transfected cells. Bar, 20 µm.