Milieu-induced, selective aggregation of regulated secretory proteins in the trans-Golgi network

The same experimental conditions were applied to control GH4C1 cells. The quantitation of [ 35 S]sulfate-labeled SgII for these and hormone-treated cells showed that, in aggregalive milieu, the ratio ofSgII in the pellet to SgII in the supernatant was increased twofold upon hormone treatment (Table II) , indicatingthat the equilibrium ofSgII between the aggregated and the nonaggregated state was shifted towards the aggregated state. These results suggest that upon hormone treatment of GH4C1 cells, there is, concomitantly with the rise in the concentration of SgII in the TGN, an increase in the proportion of SgII that is recovered in an aggregated state after incubation in aggregative milieu .