Figure 3.

Enrichment of nuclear pore proteins in HSP-2. Twenty micrograms (as determined by Bradford assay) of each fraction obtained by serial centrifugation of prophase extracts (Figure 1) was loaded onto different percentages of gels depending upon the antibody to be used, transferred to nitrocellulose, and probed with the antibodies indicated. HSP-1b was highly enriched in ER protein, GRP94 (A, lane 2), whereas HSP-1a was enriched in the mitochondrial protein VDAC (C, lane 3). HSP-2 contained three nuclear pore proteins detected by the anti-NUP antibody: NUP214, NUP153, and p62 (arrowheads in D, lane 5). HSP-2 was also enriched in γ-tubulin (B, lane 5). In all immunoblots, lane 1 contains an unfractionated HSS-1 and lane 4 contains the HSS-2 made by dilution and recentrifugation of HSS-1.