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Updated: Aug 25, 2026

Protein Purification-free Method of Binding Affinity Determination by Microscale Thermophoresis
Published on: August 15, 2013
Structure of an activated Dictyostelium STAT in its DNA-unbound form
Montserrat Soler-Lopez1, Carlo Petosa, Masashi Fukuzawa
1European Molecular Biology Laboratory, Grenoble Outstation, B.P. 181, 38042 Grenoble Cedex 9, France.
Abstract:
Dd-STATa is a STAT protein which transcriptionally regulates cellular differentiation in Dictyostelium discoideum, the only non-metazoan known to employ SH2 domain signaling. The 2.7 A crystal structure of a tyrosine phosphorylated Dd-STATa homodimer reveals a four-domain architecture similar to that of mammalian STATs 1 and 3, but with an inverted orientation for the coiled-coil domain. Dimerization is mediated by SH2 domain:phosphopeptide interactions and by a direct interaction between SH2 domains. The unliganded Dd-STATa dimer adopts a fully extended conformation remarkably different from that of the DNA-bound mammalian STATs, implying a large conformational change upon target site recognition. Buried hydrophilic residues predicted to destabilize the coiled-coil domain suggest how hydrophobic residues may become exposed and mediate nuclear export. Functional and evolutionary implications for metazoan STAT proteins are discussed.
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