GluR1 is a 4-transmembrane protein that belongs to the glutamate-gated ion channel family. It is one of four AMPA receptor subunits that form a functional heterotetrameric glutamate receptor. GluR1 only interacts with GluR2. In addition to constitutive phosphorylation on a key serine in the C-terminal extracellular region, neurotransmitter-induced phosphorylation of another key serine by CaMKII leads to a potentiation of glutamate-mediated current.