Figure 2.

Palmitoyltransferase is membrane bound. The postnuclear supernatant of HeLa cells was centrifuged at 100,000 × g for 30 min at 4°C. The pellet contained the membrane fraction (MF), and the supernatant consisted of the cytosol (Cyto). For the salt wash, the membrane fraction was subsequently incubated with 0.5 M NaCl for 30 min at 4°C and centrifuged again. The resulting pellet (P) and the supernatant (S) as well as the MF and the Cyto were assayed for palmitoyltransferase activity in vitro. Equal amounts of protein (MF, P) and according amount of supernatant (C, S) were used in the palmitoyltransferase assay .The samples were incubated with [³H]palmitoyl-CoA and purified CD-MPR at 37°C for 30 min. CD-MPR was immunoprecipitated and subjected to SDS-PAGE. [³H]Palmitate incorporation into CD-MPR was visualized by autoradiography and quantitated by densitometric scanning.