Engineering of weak helper interactions for high-efficiency FRET probes.

Fluorescence resonance energy transfer (FRET)-based detection of protein interactions is limited by the very narrow range of FRET-permitting distances. We show two different strategies for the rational design of weak helper interactions that co-recruit donor and acceptor fluorophores for a more robust detection of bimolecular FRET: (i) in silico design of electrostatically driven encounter complexes and (ii) fusion of tunable domain-peptide interaction modules based on WW or SH3 domains. We tested each strategy for optimization of FRET between (m)Citrine and mCherry, which do not natively interact.

PDGF-stimulated cell proliferation and migration of human arterial smooth muscle cells. Colocalization of PDGF isoforms with glycosaminoglycans.

Platelet-derived growth factor (PDGF) has been implicated in vascular smooth muscle cell proliferation and migration, a key process in vascular disease. PDGF is a family of dimeric isoforms of structurally related A-, B-, C- and D-chains that bind to PDGF receptors. PDGF A- and B-chains occur with and without basic C-terminal amino acid extensions as long (A(L) and B(L)) and short (A(S) and B(S)) isoforms.

Differential binding of platelet-derived growth factor isoforms to glycosaminoglycans.

The platelet-derived growth factor (PDGF) family comprises disulfide-bonded dimeric isoforms and plays a key role in the proliferation and migration of mesenchymal cells. Traditionally, it consists of homo- and heterodimers of A and B polypeptide chains that occur as long (A(L) and B(L)) or short (A(S) and B(S)) isoforms. Short isoforms lack the basic C-terminal extension that mediates binding to heparin.