Immunogold localization of endobrevin and LIMP II.
Ultrathin cryosections of NRK cells were immunolabeled for endobrevin
(15-nm protein A–gold) and either LIMP II (10-nm protein A–gold; A)
or the endogenous MPR46 (10-nm protein A–gold; B and C). Endobrevin is
detectable in tubulovesicular structures (arrows in A), underneath the
plasma membrane (PM), and on endosomal vacuoles (E) and endosomes that
appear as multivesicular bodies (MVB), where it often colocalizes with
the lysosomal membrane protein LIMP II. We also noted a colocalization
of endobrevin with MPR46 in TGN-associated structures (B, arrowheads)
and occasionally the appearance in coated pits/vesicles at the plasma
membrane (C, arrow). Bars, 100 nm.