A protein encoded by an alternative splice variant of choline acetyltransferase mRNA is localized preferentially in peripheral nerve cells and fibers

Central cholinergic systems have been visualized by immunohistochemistry us ing antibodies to choline acetyltransferase (ChAT). Peripheral cholinergic cells and fibers, however, have been hardly detectable with most of these a ntibodies. This phenomenon suggests that a different form of ChAT may exist in peripheral tissues. Here we report two types of mRNA for ChAT expressed by alternative splicing in rat pterygopalatine ganglion. One is exactly id entical with ChAT mRNA reported in the central nervous system (ChAT of a co mmon type; cChAT). The other lacks exons 6, 7, 8 and 9, which was detected only in the pterygopalatine ganglion (ChAT of a peripheral type; pChAT). Th e peculiarity of pChAT in chemical structure, possessing a splice joint of the exons 5 and 10, led us to produce rabbit antisera against a recombinant peptide of 41 amino acids which spans over the splice joint. On Western bl ots using a successfully obtained antiserum, an intense band of about 50 kD a, corresponding to the expected molecular weighs of pChAT, was detected in the pterygopalatine ganglion but not in the brain. Immunohistochemistry us ing the antiserum failed to reveal positive staining of known brain choline rgic structures, while it permitted us to observe peripheral, probably chol inergic, nerve cells and fibers including those in the pterygopalatine gang lion and enteric nervous system. (C) 2000 Elsevier Science B.V. All rights reserved.