Cloning of novel splice variants of mouse mGluR1.

Three splice variants of the mouse metabotropic glutamate receptor 1, mGluR1E55, mGluR1a and mGluR1b, have been isolated from mouse brain cDNA libraries. The sequences of mGluR1a and mGluR1b are similar to those from rat and human. mGluR1E55 is a novel splice variant. mGluR1E55 has two additional exons. One is 80-bp long at the 5' untranslational region. The other (E55) is 110-bp long at the cysteine-rich region after the ligand-binding domain and before the seven-transmembrane domain. Insertion of the E55 exon results in an inframe stop codon. The predicted protein product contains only the extracellular domain of the receptor and may be secreted.