Human platelet glycoproteins IIb (GPIIb) and IIIa (GPIIIa) form the subunits of the Ca(2+)-dependent heterodimer GPIIb/IIIa, which belongs to the integrin family of phylogenetically related receptors mediating a wide variety of cell-cell and cell-substratum interactions. GPIIb/IIIa plays a central role in haemostasis as a receptor for fibrinogen and other adhesive proteins at the surface of act...

The yeast kinesin motor protein Kar3 forms a heterodimer with a nonmotor protein Vik1. A study in this issue by Allingham et al. (2007) reveals that Vik1 unexpectedly has a structure similar to a kinesin motor domain yet lacks a nucleotide-binding site and is thus catalytically inactive. However, this does not hinder movement of the heterodimer because other features of the remarkably divergent...

The interaction of the serine/threonine kinase Pelle and adaptor protein Tube through their N-terminal death domains leads to the nuclear translocation of the transcription factor Dorsal and activation of zygotic patterning genes during Drosophila embryogenesis. Crystal structure of the Pelle and Tube death domain heterodimer reveals that the two death domains adopt a six-helix bundle fold and ...

PPARγ is a key regulator of glucose homeostasis and insulin sensitization. PPARγ must heterodimerize with its dimeric partner, the retinoid X receptor (RXR), to bind DNA and associated coactivators such as p160 family members or PGC-1α to regulate gene networks. To understand how coactivators are recognized by the functional heterodimer PPARγ/RXRα and to determine the topological organization o...

KDM2B recruits H2A-ubiquitinating activity of a non-canonical Polycomb Repression Complex 1 (PRC1.1) to CpG islands, facilitating gene repression. We investigated the molecular basis of recruitment using in vitro assembly assays to identify minimal components, subcomplexes, and domains required for recruitment. A minimal four-component PRC1.1 complex can be assembled by combining two separately...

Following the earlier work of Yang et al. [J. Chem. Phys. 110 (1999) 2983] analytical expressions for the downhill and uphill resonant two-color three-pulse photon echo peak shift (2C-3PEPS) of a heterodimer system are derived in the impulsive limit. It is shown how to obtain information about coupling between the components of the dimer from the combined one- and two-color peak shift measureme...

The 38 kD molecule is noncovalently associated with beta 2 microglobulin (beta 2m)-free HLA heavy chain-like molecule, and thus forms a second heterodimer distinct from the clonotypic alpha/beta T cell receptor expressed by the same clone of leukemia cells. This second heterodimer (38 kD/HLA) is variably expressed and appears to be associated with the T3 molecule. We suggest, therefore, that it...

The proteins Ctf19, Okp1, Mcm21 and Ame1 are the components of COMA, a subassembly of budding-yeast kinetochores. We have determined the crystal structure of a conserved COMA subcomplex--the Ctf19-Mcm21 heterodimer--from Kluyveromyces lactis. Both proteins contain 'double-RWD' domains, which together form a Y-shaped framework with flexible N-terminal extensions. The kinetochore proteins Csm1, S...

While the signaling properties of ubiquitin depend on the topology of polyubiquitin chains, little is known concerning the molecular basis of specificity in chain assembly and recognition. UEV/Ubc complexes have been implicated in the assembly of Lys63-linked polyubiquitin chains that act as a novel signal in postreplicative DNA repair and I kappa B alpha kinase activation. The crystal structur...

Various approaches have been used to modulate the fluorescence changes of sensors in the presence of target analytes, including intramolecular interaction between fluorophores or between fluorophore and other molecular species, like resonance energy transfer (RET). Here, we focus on fluorescence quenching by intramolecular heterodimer complex formation, which can be modulated over a shorter dis...