heparinbinding

Heparinbinding refers to the property of a molecule to bind heparin, a highly sulfated glycosaminoglycan commonly used as an anticoagulant. In biology, many proteins possess heparinbinding capacity, enabling interactions with heparan sulfate proteoglycans on cell surfaces and in the extracellular matrix. These interactions influence localization, stability, and signaling.

Binding typically arises from electrostatic attraction between positively charged amino acids (lysine and arginine) and the sulfate groups on heparin. Several binding motifs have been described, including the Cardin–Weintraub motif XBBXBX (B = basic residue), which helps predict potential heparinbinding regions. Structural context and the presentation of basic residues modulate affinity and specificity.

Biological roles of heparinbinding include participation in anticoagulant pathways and growth factor signaling. For example, antithrombin binds heparin to accelerate its inhibition of thrombin. Heparinbinding also facilitates signaling by fibroblast growth factors (FGF1/FGF2) and their interaction with FGFRs, and it contributes to processes such as chemokine activity, angiogenesis, wound healing, and development. Some extracellular matrix proteins and microbial or viral proteins use heparinbinding to mediate adhesion or host interactions.

Examples of well-known heparinbinding proteins include antithrombin, heparin-binding EGF-like growth factor (HB-EGF), FGFs, CXCL12, and VEGF family members. Binding affinity is variable and can be transient or strong, depending on the sulfation pattern of surrounding glycans and cellular context.

Research methods to study heparinbinding include heparin affinity chromatography, surface plasmon resonance, isothermal titration calorimetry, and mutational analysis to identify critical basic residues. Structural studies and computational predictions further illuminate binding motifs and mechanisms.