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Research Focus 2: Biochemical and Structural Characterization of IQD-Assembled Macromolecular Protein Complexes

Proteins often function as part of larger complexes, interacting non-covalently to perform specialized tasks. In plant cells, microtubule-associated proteins (MAPs), including IQD proteins, assemble into macromolecular complexes that regulate microtubule dynamics and cellular functions. IQDs are proposed to act as scaffolds within these complexes, connecting various proteins and integrating different signals. Their structure, characterized by short, conserved motifs and intrinsically disordered regions (IDRs), enables flexible interactions with multiple binding partners within protein-protein interaction (PPI) networks. Consistent with proposed functions as cellular scaffolds, our research has identified several interacting proteins that bind to distinct IQD motifs. To further understand IQD functions, we are investigating how phosphorylation and CaM binding contribute to IQD specificity through detailed structural studies. Using recombinant expression and purification techniques, we characterize IQD structures and their complexes using cross-linking MS, cryo-EM, and X-ray crystallography. These studies will provide insights into the assembly and regulation of protein complexes, helping us understand how IQDs contribute to plant growth regulation.