A membrane receptor for gangliosides is associated with central nervous system myelin

A binding protein specific for major neuronal gangliosides was detected on rat brain membranes using a synthetic ganglioside-protein conjugate, ¹²⁵I-(G(T1b)₄BSA (bovine serum albumin derivatized with 4 mol of ganglioside G(T1b)/mol of protein), as a radioligand. Specific binding of the ligand displayed marked regional variation within the brain, with white matter-enriched regions demonstrating the highest binding activity. Autoradiographic localization of ¹²⁵I-(G(T1b))₄BSA binding to tissue sections revealed selective asociation with myelinated pathways throughout the brain. The ligand also bound preferentially to brain subcellular fractions enriched in myelin, even after removal of axolemma. In contrast, peripheral nerve myelin had little binding activity. The myelin-associated ganglioside receptor detected by ¹²⁵I-(G(T1b))₄BSA binding appears to be a novel oligodendroglial membrane protein which preferentially recognizes neuronal gangliosides.