Figure 4.

Analysis of membrane association of endogenous and mutant lamin B3 variants by floating gradient centrifugation. Wild-type and mutant lamin B3 variants were expressed in oocytes by RNA injection. Oocytes were matured to eggs with progesterone, and egg homogenates were prepared by low-speed centrifugation. Membranes were separated from soluble proteins by floating gradient centrifugation of egg homogenates (see MATERIALS AND METHODS). Aliquots of the gradient fractions were separated by SDS-PAGE, and lamins were detected by immunoblotting with mAb L6-5D5 (A) or mAb M2 (B–H). The loading zones in A–H and the flotation zone in H are indicated by brackets. Note that the two fractions of the bottom of gradients B–H are not shown. The names of the lamin B3 constructs are given at left. The sequences of the last exon of these constructs are listed in Table 1.