Heparan sulfate gets specific

Proteoglycans on the cell surface can exhibit a baffling diversity of structures, but the relative importance of that diversity in controlling the specificity of interactions between proteins is not known. On page 845, Allen et al. demonstrate that heparan sulfate serves as a tissue-specific regulator of interactions between FGF family members and FGF receptors. Besides providing important insight into the mechanism of FGF signaling, the work suggests that specific heparan sulfate sequences on a cell's surface can determine the cell's ability to respond to exogenous signals.

The formation of an FGF signaling complex requires that both an FGF-family protein and its receptor interact with a heparan sulfate proteoglycan, but little was known about the function of heparan sulfate in this complex. The authors probed frozen tissue sections of mouse embryos with FGF-2...