Distribution of Syn7 and Syn13 in WIF-B cells by
confocal microscopy. Polarized WIF-B cells were fixed and permeabilized
and then double-labeled with antibodies to Syn7 and lgp120 (A), Syn13
and lgp120 (B), or Syn13 and TfR (C). Mouse mAbs were used to label
Syn7 (A), lgp120 (B), and TfR (C) with rabbit polyclonal antibodies
labeling lgp120 (A) and Syn13 (B and C). FITC-conjugated antibodies to
mouse IgG (A, Syn7; B, lgp120; C, TfR) and Cy3-conjugated antibodies to
rabbit IgG (A, lgp120; B and C, Syn13) were used as secondary
antibodies. Optical sections in A and B are through the middle of the
cells, whereas the section in C is slightly closer to the substratum to
show more peripheral endosomes. Arrows point to structures that are
positive for two markers, and arrowheads point to structures that are
positive for only one marker. Note the good coincidence of Syn7 with
lgp120-positive structures, i.e., lysosomes (A), and of Syn13 with TfR,
i.e., early endosomes (C), whereas little overlap is seen between Syn13
and lgp120 (B). BC, bile canalicular-like space; N, nucleus. Bar, 10
μm.