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Fig. 3 | Cell Communication and Signaling

Fig. 3

From: Motif co-regulation and co-operativity are common mechanisms in transcriptional, post-transcriptional and post-translational regulation

Fig. 3

Distinct regulatory programs and protein modularity. a The higher eukaryotic cell has a large repertoire of protein modules, represented here by different shapes with different colours, that are reused by evolution to encode many aspects of protein functionality, including its subcellular localisation (pentagons), stability (triangles), modification state (circles) and interactome (rectangles). The ex nihilo acquisition of a targeting SLiM can result in protein relocalisation. For instance, while a protein without an NLS motif (top) is expressed ubiquitously throughout the cytoplasm (blue zone), acquisition of an NLS motif (bottom, red pentagon) results in specific localisation of the protein in the nucleus (blue zone). b The ex nihilo acquisition of a degradation motif can result in changes to the temporal, spatial or conditional local abundance of a protein. For instance, while the abundance of a protein without a cell cycle-specific degron (top) is independent of the different phases of the cell cycle, acquisition of a cell cycle-specific degron (bottom, green triangle), for example a D box motif, allows the abundance of the protein to be adjusted for a specific phase of the cell cycle. c Example of co-regulation of a protein by the same motif (boxed blue pentagon). The three different proteins will be regulated in a similar manner under specific conditions through recruitment of the same binding partner by the shared motif, for instance cell cycle-dependent degradation of cell cycle regulators such as Acm1 [156], Cyclin A [157] and Securin [158], which are targeted to the APC/C for ubiquitylation through their D box motifs. d Proteins with instances of the same globular domain (boxed brown rectangle) can have hugely different life cycles depending on the set of motifs present in the protein. While the proteins have a similar activity due to the shared globular domain, their distinct motif content subjects them to specific regulatory programs and diversely controls their life cycle, as is the case for the different members of the CDC25 family of phosphatases [117] and the Cyclin-dependent kinase inhibitor family [118]

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