Table I.
Determination of the Fusion Efficiency
| PNS | PNS | VG | ||||
|---|---|---|---|---|---|---|
| PC2-ISGs fusion NR* + processing ip 175 | hybrid ISGs + fusion + processing ip 175 | hybrid ISGs + fusion + processing total p86 | ||||
| p86 in starting material (st) | 76.0 | 62.73 | 34.2 | |||
| p86 after incubations (fin) | 23.6 | 46.76 | 20.8 | |||
| Percent processing efficiency | 69.0% | 25.5% | 39.2% | |||
| (p86st − p86fin) × 100 | ||||||
| (p86st) | ||||||
| Percent fusion efficiency | 100% | 37% | — |
NR, not required. A PNS was prepared from PC12 or PC12/PC2 cells labelled for 30 min with [35S]sulphate. Fusion assays were performed as described using a PNS or enriched fractions (VG). The amount of p86 before (starting material = st) and after the fusion reaction (final = fin) was determined by immunoprecipitation with Ab 175 (ip 175) or by direct analysis of the total p86 from enriched fractions containing ISGs (Fig. 5) and is expressed as arbitrary units. Processing efficiency is calculated from the values shown which are from representative experiments. Fusion efficiency in hybrid ISGs was expressed as a percentage of SGII processing in intact PC2-ISGs using the values obtained with the PNS samples.