The identity of α1 subunits from voltage operated Ca2+ channels was determined in the rat/mouse mesencephalon × N18TG2 hybridoma cell line MES23.5, by sequence analysis of reverse transcription-polymerase chain reaction products and antagonist binding. Sequences were derived from the L-(α1D, Q-(αA) and ω-contoxin GVIA sensitive N-type (α1B) Ca2+ channel α1 subunits. The amplified fragments, which are homologous to the region between domain III and IV of known α1 subunits, reveal splice variation in the L- and Q-type α1 subunit of MES23.5 cells. The transcripts of α1 subunits in these cells were quantified by RNAase protection assay. The data show the existence of different Ca2+ channel types in a single cell line and may reflect multiple functions of voltage operated Ca2+ channels during growth, differentiation and transmitter release.
ASJC Scopus subject areas