Identification of some lectin IB4 binding proteins in rat dorsal root ganglia

Lectins are proteins that bind to glycoproteins and glycolipids. The isolectin Griffonia simplicifolia I-B4 (IB4) recognizes terminal cc-galactose and binds to a subset of small and medium-sized neurons in the dorsal root ganglia (DRG). Using one and two-dimensional gel electrophoresis, we have identified several proteins that bind IB4 in sciatic nerve, dorsal horn, and DRG. Treatment with the enzyme alpha-galactosidase reduces IB4 binding, strongly suggesting the binding is specific for the IB4 epitope. Mass spectrometric analysis of tryptic digests of alpha-galactosidase sensitive bands identified three proteins that bind IB4: the laminin beta2 chain and the light and medium subunits of neurofilaments.