Impaired ribosomal subunit association is SBDS-dependent. Ribosomal subunit association was assayed in SDS patient-derived bone marrow stromal cells infected with lentiviral vectors encoding WT or mutant (K33E, R126T, R169C) SBDS cDNA. Empty vector was used as a control (Ctrl). (A) SBDS protein expression was assayed by immunoblot for each condition. (B) Cells were lysed in 0.25mM MgCl2 to dissociate the ribosomal subunits. After the MgCl2 concentration was raised to 10mM, ribosomal subunit association was measured as described in Figure 3. Ribosomal profiles from WT SBDS (dotted lines) are overlaid for comparison with empty vector control or SBDS point mutants (solid lines). Representative polysome profiles are shown. (C) The 80S:40S ratio was quantitated for 3 independent experiments; *P < .05, **P < .01.
