(D) Sucrose density gradient sedimentation profile of ribosomal proteins and mtRNAs from heartmitochondria. The migration of ribosomal subunits (28S and 39S) and mitoribosome (55S) was detected by immunobloting with antibodies against MRPS35 and MRPL12. The profile of a given mt-RNA is calculated after qRT-PCR analysis of individual fractions and corrected for its abundance in the cell according to results of Northern blot analysis. Results of individual experiments are provided for 12S and 16S rRNA, and for mt-mRNAs, results of distribution from two independent experiments using probes against ATP6, COXIII and ND5 were combined. Error bars represent mean ± SD. Student's t-test was used to determine the level of statistical difference (n=3). 