(A) Sucrose density gradient sedimentation profile ("short gradients") of ribosomal proteins and transcripts from control (Clpp+/+) and Clpp knockout (Clpp-/-) heartmitochondria. The migration of ribosomal subunits (28S and 39S) and mitoribosome (55S) was detected by immunoblotting with antibodies against MRPS35 and MRPL12. 12S rRNA was analysed by Northern blot. 