ALTERNATIVE SPLICING GENERATES METABOTROPIC GLUTAMATE RECEPTORS INDUCING DIFFERENT PATTERNS OF CALCIUM RELEASE IN XENOPUS OOCYTES

A splice variant of the metabotropic glutamate receptor (mGluR) 1a, named mGluR1c, was isolated. Compared to mGluR1a, the predicted mGluR1c protein is 302 amino acids shorter at its C-terminal end. Despite this difference, mGluR1c activates phospholipase C in Xenopus oocytes with a pharmacological profile identical to that of mGluR1a. However, in contrast to the large fast transient responses induced by mGluR1a, mGluR1c receptors elicit a small more slowly generated long-lasting oscillatory current, suggesting that these two receptors do not generate the same pattern of Ca2+ release in Xenopus oocytes. In situ hybridization data show that mGluR1c mRNA is expressed at a lower level than the other splice variants of mGluR1. Some differences in the regional distribution of these transcripts were observed in the cerebellum, the olfactory bulb, and the striatum.