[Existence of UDP galactose: galactosyltransferase activity at the external surface of cultured neurons].

The existence of UDP-galactose:galactosyltransferase activities at the external surface of cultured neurons from chick embryo hemispheres, was demonstrated. [14C]-galactose was transferred upon cellular substrates present on the neuronal surface and upon exogenous substrates (ovomucoïd) bound to Sepharose beads. The activity of ectogalactosyltransferase was not due to a leakage of intracellular enzymes into the incubation medium nor to an intracellular enzymatic activity utilizing [14C]-galactose obtained from the hydrolysis of UDP-[14C]-galactose. Kinetics of these ectogalactosyltransferases were analysed. The results support the hypothesis of a communication and/or interaction among the nerve cell surfaces via glycoconjugates or their biosynthetic enzymes.