Fig. 1.
Human proteins can be post-translationally translocated across the ER membrane. Opsin epitope-tagged forms of ppcecA, apelin and statherin (supplementary material Fig. S1) were synthesised in vitro using rabbit reticulocyte lysate and [35S]methionine. Canine pancreatic microsomes were added and samples incubated at 30°C to allow translocation. The membrane fraction was isolated and analysed following Endo H treatment, SDS-PAGE and phosphorimaging. The N-glycosylated species (1, singly N-glycosylated; 2, doubly N-glycosylated), processed (p) and unprocessed forms (pp) of all precursors are indicated. Positions of molecular size markers are indicated on the left in kDa.