ProteinAssemblies

ProteinAssemblies refer to organized structures formed when multiple protein molecules come together through specific interactions to perform biological functions. They span a wide size range, from small dimers to large supramolecular complexes, and may include cofactors, nucleic acids, or lipids that contribute to stability and activity. Assembly can be fixed in composition or variable, and assemblies often assemble in particular cellular locations or in response to cellular signals.

Common examples include ribosomes, which combine ribosomal RNA and proteins to synthesize proteins; proteasomes that degrade unwanted polypeptides; chaperonins such as GroEL/GroES that assist protein folding; and viral capsids formed by coat proteins enclosing genetic material. Other assemblies include spliceosomes, transcriptional regulatory complexes, and cytoskeletal structures like microtubules and actin bundles. These complexes can be dynamic, exchanging subunits or shifting conformations during activity.

Formation is governed by principles of protein chemistry, including stoichiometry, affinity, and allosteric regulation. Assembly often proceeds via nucleation followed by elongation, and cellular systems use chaperones, scaffolds, and post-translational modifications to ensure correct assembly and prevent misfolding. Misassembly or abnormal aggregation can contribute to disease, such as neurodegenerative conditions involving amyloid or prion-like assemblies.

Technologies such as cryo-electron microscopy, X-ray crystallography, cross-linking mass spectrometry, and computational modeling are used to study the structure and dynamics of protein assemblies. Understanding their organization and regulation provides insight into fundamental biology and approaches for therapeutic intervention.