Figure 2

Immunoblot analysis of samples fractionated by two phase affinity partitioning using 6.3%PEG/Dextran. A - Fractionation of microsomes prepared from heads. Only small amounts of Nervana are recovered in the ConA fraction, and these contain significant amounts of the ER marker BiP. Labeling: P100 - input microsomes from the 100,000 × g pellet; D1-3 - Dextran fractions D1-3 in figure 1; P1+P2, P3 - PEG fractions P1-3 in figure 1; ConA - eluate released from the ConA-dextran fraction DC in figure 1. All samples represent remaining protein after each fractionation step. Asterisk - non-specific antibody binding to a large amount of ConA that coelutes from the dextran. Nrv - Nervana; BiP - ER chaperon BiP; ATP - α subunit of the mitochondrial F₁F₀ ATPase; αSp - α-Spectrin. Loading: All samples have equivalent loading, except P100, which was 1/5^th of the others. Detection: normal sensitivity chemiluminescence (see Methods). B - Fractionation of microsomes prepared from 0-15 hr embryos. Only small amounts of α-Spectrin are recovered in the ConA fraction. This fraction also contains readily detectable amounts of the ER marker BiP and small amounts of ATP synthase from mitochondria. Labels, loadings and detection are the same as A.