A full‐length cDNA which encodes a putative glutamate receptor polypeptide was isolated from the pond snailLymnaea stagnalis, using a short stretch of exonic sequence and two variants of the polymerase chain reaction. In this first comparison of invertebrate and vertebrate glutamate receptor sequences, the mature molluscan polypeptide, which comprises 898 amino acids and has a predictedM r of 100 913, displays between 37% and 46% amino‐acid identity to the rat ionotropic glutamate receptor subunits, GluR1 to GluR6.
