FIGURE 4.

CerS5 and CerS 2 activity in chimeras containing the N terminus of CerS5 and the C terminus of CerS2. A, homogenates (100 μg of protein) were prepared from cells overexpressing the indicated constructs (for terminology, see Fig. 2). CerS5 activity was assayed using C16-CoA (upper panel) and CerS2 using C22-CoA (lower panel). Results are the means ± S.D. of a typical experiment repeated three times with similar results. *, p < 0.05. B, putative membrane topology of each construct is shown. The topology is based on six predicted transmembrane domains (Fig. 1); regions provided by CerS5 are shown in dark gray and CerS2 are in light gray.