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Research has been conducted on the PDZ modular protein-protein interaction domains that bind to specific C-terminal membrane protein sequences. The generation of the recombinant PDZ domains of PSD-95 and syntrophins with single-amino acid substitution altering the binding specificity and affinity is described.

Researchers have developed a pro-apoptotic peptide that targets new blood vessels produced by tumors and destroys them by disrupting mitochondrial membranes. The peptide is non-toxic outside of cells but induces cell death when internalized.

The intracellular receptor autophosphorylation on tyrosine residues causes accumulation of different proteins with SH2 domains including c-src, during the signal transduction activated by epidermal growth factor. c-src and epidermal growth factor receptor (EGFR) kinase activities phosphorylate in vitro the C-terminal autophosphorylation domain of EGFR. The SH2 domain of c-src interacts with certain EGFR c-src phosphorylation sites. Such interaction is responsible for the regulation of growth factor receptor activity and signal transduction.

The proteins commonly referred to as 14-3-3s have recently come to prominence in the study of protein:protein interactions, having been shown to act as allosteric or steric regulators and possibly scaffolds. The binding of 14-3-3 proteins to the regulatory phosphorylation site of nitrate reductase (NR) was studied in real-time by surface plasmon resonance, using primarily an immobilized synthetic phosphopeptide based on spinach NR-Ser543. Both plant and yeast 14-3-3 proteins were shown to bind the immobilized peptide ligand in a Mg2+-stimulated manner. Stimulation resulted from a reduction in KD and an increase in steady-state binding level (Req). As shown previously for plant 14-3-3s, fluorescent probes also indicated that yeast BMH2 interacted directly with cations, which bind and affect surface hydrophobicity. Binding of 14-3-3s to the phosphopeptide ligand occurred in the absence of divalent cations when the pH was reduced below neutral, and the basis for enhanced binding was a reduction in KD. At pH 7.5 (+Mg2+), AMP inhibited binding of plant 14-3-3s to the NR based peptide ligand. The binding of AMP to 14-3-3s was directly demonstrated by equilibrium dialysis (plant), and from the observation that recombinant plant 14-3-3s have a low, but detectable, AMP phosphatase activity. [ABSTRACT FROM AUTHOR]