Binding of tetanus toxin to somatic neural hybrid cells with varying ganglioside composition

125I-labelled tetanus toxin interaction with several somatic hybrid cell lines was investigated. Binding of toxin is most effective in NCB-20, followed by NBr-10A, NG108-C15, and SB21-B1 cells. Specific binding of toxin to NCB-20 and SB21-B1 cells is 7- and 60-fold lower, respectively, in comparison to enriched rat cerebral neuron cultures. The NCB-20, NBr-10A, and NG108-C15 clones display a complex ganglioside pattern, including the presence of N-acetyl-neuraminyl]-galactosyl-N-acetylgalactosaminyl N-acetylneuraminyl]-galactosylglucosyl-ceramide (GD1a) and two unidentified 14C]galactose-labelled lipid-soluble compounds, while the SB21-B1 is most abundant in N-acetyl-neuraminyl]-galactosylglucosyl-ceramide (GM3) and N-acetyl-galactosaminyl-N-acetyl-neuraminyl]-galactosylglucosyl-c eramide (GM2) gangliosides. None of the cells tested contain measurable levels of 14C]galactose-labelled or resorcinol-positive bands of galactosyl-N-acetyl-galactosaminyl- N-acetylneuraminyl-N-acetylneuraminyl]-galactosylglucosyl-ceramide (GD1b) and N-acetylneuraminyl]-galactosyl-N-acetylgalactosaminyl- N-acetylneuraminyl-N-acetylneuraminyl]-galactosylglucosyl-ceramide (GT1b) gangliosides. After 2 h at 37 degrees C a near plateau of toxin association with NCB-20 cells is seen. Binding in low-ionic-strength medium is 1.35-fold higher at 37 degrees C than at 4 degrees C, but is reduced by 21 and 51% at 4 degrees C and 37 degrees C, respectively, in physiologic medium. Treatment of NCB-20 cells with neuraminidase causes a partial loss (29%) of toxin-binding sites. Binding to the hybrid cells is significantly different from that of cerebral cultures with respect to temperature, salt effect, and sensitivity to neuraminidase, suggesting perhaps a different class of receptors for the toxin.(ABSTRACT TRUNCATED AT 250 WORDS)