Fig. 8. Immuno-absorption of vesicles from TGNs by antibodies against Sbr I and Sbr II. Equal amounts of the total membrane fraction from lysed TGNs were incubated overnight at 4°C with protein A beads coupled to IgGs specific for Sbr I or SbrII, or rabbit non-immune IgG (control). After extensive washing, equivalent aliquots of beads were sedimented and pellets dissolved in SDS sample buffer for SDS-PAGE and western blotting. Alternatively, 2 M acetic acid with 0.1% TFA was added to replicate samples for CGRP determination. (A) CGRP content (± s.e.m.) measured in two separate preparations show the large enrichment in vesicles obtained using beads containing Sbr I or Sbr II relative to the control. (B) Western blots of the two vesicle preparations and the control, using antibodies specific for Sbr I or Sbr II.