Evidence for clustered mannose as a new ligand for hyaluronan-binding protein (HABP1) from human fibroblasts

We have earlier reported that overexpression of the gene encoding human hya luronan-binding protein (HABP1) is functionally active, as it binds specifi cally with hyaluronan (HA). In this communication, we confirm the collapse of the filamentous and branched structure of HA by interaction with increas ing concentrations of recombinant-HABP1 (rHABP1). HA is the reported ligand of rHABP1. Here, we show the affinity of rHABP1 towards D-mannosylated alb umin (DMA) by overlay assay and purification using a DMA affinity column. O ur data suggests that DMA is another ligand for HABP1. Furthermore, we have observed that DMA inhibits the binding of HA in a concentration-dependent manner, suggesting its multiligand affinity amongst carbohydrates. rHABP1 s hows differential affinity towards HA and DMA which depends on pH and ionic strength. These data suggest that that affinity of rHABP1 towards differen t ligands is regulated by the microenvironment.