Figure 1

PPIs (black) and structural SDDIs (red). (a) Theme of three PPI-SDDI-PPI triangles sharing the same SDDI. The red SDDI edge is involved in all three triangles. Proteins D 1 and D 2 may interact physically with C in the cytoskeleton, or R in the ribosome, or N in the nucleus. The transitive module hypothesis suggests two proteins such as D 1 and D 2 that share many common interaction partners are more likely to interact than two proteins that share few common interaction partners [9]. Some PPIs have no common Gene Ontology annotation, hinting to false positives.(b),(c) Biological examples of myosin-actin involvement in multiple processes/locations. Their representation as PPI-SDDI-PPI triangle network motifs and themes, as found in integrations of PPINs with SDDIs. (b) Myosin in actin cytoskeleton organization and formation. Myosin mediates actin remodelling and vesicular transport. (c) Actin and nuclear myosin I (NMI) are required for transcription by RNA polymerases (Pols) I, II, III in the eukaryotic cell nucleus. Actin is directly associated with Pol I, regardless of whether Pol I is engaged in transcription, and NMI interacts with transcription initiation factor TIFIA. TIFIA is phosphorylated. Pol I is then recruited to the DNA promoter through interaction with the phosphorylated TIFIA, which brings actin and NMI into close proximity with each other. Actin, but not NMI, remains associated with Pol I during transcription elongation [121–124].