Figure 6.

Fractionation of whole cell extracts. (A) Cellular extract of strain BY251 [URE3] variant 1 was fractionated (see Materials and methods) and transformed into BY241. The starting concentration was 25 mg/ml; relative amounts of Ure2p were estimated by determining whole protein concentration and relative Ure2p content in each fraction (see Materials and methods). Similar results were obtained with cell extracts from different strains and [URE3] variants (data not shown). (B) Fractionation does not interfere with faithful transmission of [URE3] characteristics to the transformants. All randomly chosen transformants resulting from a transformation with BY241 [URE3] variant 1 extract fractions show the characteristic white appearance on 1/2 YPD plates. Extract fractionation was performed as in previous experiments, except that pelleting was performed at 45 000 g for 45 min.