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

A Con A-binding glycoprotein of Mr 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.