Analysis of 953 Human Proteins from a Mitochondrial HEK293 Fraction by Complexome Profiling
Figure 5
Identified mitochondrial ribosomal complexes by hierarchical clustering.
Subunits of the mitoribosome were predominantly found in 4 distinct complexes by the HCL analysis as shown in figure 5A. Known subunits of the mitoribosome are bold red whereas proven interactors are in black and bold underlined. Proteins previously co-purified with mitoribosomal subunits are italic. The majority of detected MRPL subunits co-migrate in a complex of about 3 MDa in size which is referred to as the 39 S mitoribosome complex in this paper. Besides MRP subunits, six other proteins showed co-migration of which ICT1 is a proven interactor of the mitoribosome. The remaining three proteins DBT, STOML2, and CAD have previously been reported to co-purify with mitoribosomal proteins in affinity purification – mass spectrometry studies. Similar to MRPL proteins, all but one of the 28 S mitoribosomal MRPS subunits showed to co-migrate in a complex of about 1.6 MDa together with 12 other proteins that include the known mitoribosome interactor PTCD3. Four of the remaining 11 proteins have been reported to co-purify with mitoribosomal subunits in affinity purifications.This complex is referenced in the text as the 28 S mitoribosome complex.Figure 5A also shows a smaller complex of about 300 kDa in size that includes 8 MRPS and 3 MRPL subunits of the mitoribosome together with SARM1.Finally, another complex of about 200 kDa in size was detected that appears to consist of five mitoribosomal proteins together with LRPPRC, C14ORF156 (SLIRP), and COX7A2. Figure 5B shows the distribution of MRP subunits versus non-MRP proteins detected in any of the four complexes and Figure 5C shows the distribution of the 21 non-MRP proteins in three classes: proven interactors, proteins co-purified with mitoribosomal proteins in affinity purification – mass spectrometry studies, and proteins that have thus far not been described in literature related to the mitochondrial ribosome.