Immunological and pharmacological heterogeneity of alpha-bungarotoxin binding sites extracted from TE671 cells

A proportion of the acetylcholine receptors (AChR) extracted from the human medulloblastoma cell line, TE671, differed pharmacologically and immunologically from AChR extracted from ischaemic human calf muscle (HCM). 29.6% (mean value) of the total 125I-alpha-bungarotoxin (alpha-BuTx) binding sites in the TE671 extracts was not inhibited by d-tubocurarine (dTC). Three of five monoclonal antibodies (m.abs), all of which precipitated greater than 80% of HCM AChRs, precipitated less than 55% of the total TE671 AChR. However, myasthenia gravis sera bound to TE671, and TE671 cell surface AChRs appeared to be similar to that of HCM.