Studies on the 240-kDa Con A-binding glycoprotein of rat cerebellum, a putative marker of synaptic junctions

A Con A-binding glycoprotein of M r 240,000 was isolated from the remaining residue of rat cerebella after sequential extraction with buffers supplemented with or without neutral detergents. It was further purified by affinity chromatography on Con A-Sepharose in the presence of sodium dodecyl sulfate and preparative gel electrophoresis. This glycoprotein partially resists Triton X-100 extraction and is soluble in N-lauryl sarcosinate. The 240-kDa glycoprotein was not detected in kidney, liver, heart, forebrain and was specifically seen in cerebellar homogenate. The isolated glycoprotein appears to be similar, not necessarily identical with the GPA — a synaptic junction 240-kDa Con A-binding glycoprotein isolated from cerebellum earlier (Groswald and Kelly, J. Neurochem., 42 (1984) 534–546). Monospecific antibodies obtained against the purified 240-kDa protein were used for developmental study in normal and hypothyroid rats. There was observed an increase in the amount of 240-kDa glycoprotein, dependent on the age of the rat and this rise was in correlation with the synapse formation in rat cerebellum. The amount of 240-kDa glycoprotein is considerably reduced in hypothyroid rats.