Macromolecular complexes as depots for releasable regulatory proteins
Partho Sarothi Ray1, Abul Arif, Paul L Fox
1Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue/NC10, Cleveland, OH 44195, USA.
Abstract:
Multi-component, macromolecular complexes perform essential cellular functions that require spatial or temporal coordination of activities. Complexes also facilitate co-regulation of protein amounts and cellular localization of individual components. We propose a novel function of multi-component complexes as depots for regulatory proteins that, upon release, acquire new auxiliary functions. We further propose that component release is inducible and context-dependent. We describe two cases in which multi-component assemblies - the ribosome and tRNA multi-synthetase complex--function as depots. Both complexes have crucial roles in supporting protein synthesis but they also release regulatory proteins for inflammation-responsive, transcript-specific translational control. Recent evidence indicates that other macromolecular assemblies might be sources for proteins with auxiliary functions, and the depot mechanism might be widespread in nature.
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