EAAT4, A GLUTAMATE TRANSPORTER WITH PROPERTIES OF A CHLORIDE CHANNEL,IS PREDOMINANTLY LOCALIZED IN PURKINJE-CELL DENDRITES, AND FORMS PARASAGITTAL COMPARTMENTS IN RAT CEREBELLUM

Glutamate transporters play a pivotal role in terminating glutamatergi c transmission by eliminating glutamate from the synaptic cleft.(12) F our different glutamate transporter cDNAs have been isolated thus far, and their tissue distribution has been investigated using northern bl ot and immunohistochemical analysis.(5,9,11,14,15,17) We raised site-d irected antisera against a synthetic oligopeptide corresponding to the C-terminal of EAAT4, a recently cloned human glutamate transporter, a nd investigated the distribution of EAAT4 in rat cerebellum. Western b lot analysis demonstrated that the affinity-purified antiserum SAE4 re cognized specifically a single band (about 62 kDa) in the rat cerebell um, cerebrum and spinal cord. The SAE4-immunoreactivity was localized predominantly in the dendritic spines and distal dendrites of Purkinje cells. The intensity of the immunoreactivity was uneven among Purkinj e cells, forming parasagittal compartments. Since EAAT4 also has the p roperties of a glutamate-gated chloride channel, it should be able to modulate the transmission at the parallel fiber-Purkinje cell synapses . (C) 1997 IBRO. Published by Elsevier Science Ltd.