Figure 1. Transmembrane topology and location of functionally important residues in GlyR ₁ (red) and (blue) subunits. Cylinders represent the four presumed membrane-spanning domains (M1–M4). Regions involved in subunit processing and receptor assembly are indicated by green circles. Conserved cysteine residues that are thought to form disulfide bridges are indicated by black circles. Natural point mutations (yellow circles): Mutation A52S is found in the GlyR ₁ subunit gene in spasmodic mice and decreases agonist affinity; mutations I244N, R271Q/L, K276E and Y279C are found in the GlyR ₁ subunit gene in different hyperexplexia families and result in an uncoupling of ligand binding and channel gating. Agonist and antagonist binding (blue circles): In the GlyR ₁ subunit residues G160, K200 and Y202 are involved in strychnine binding, the efficacy of the taurine is determined by residues I111 and A212; F159, Y161 and T204 are determinants of agonist specificity and affinity. Channel function: G254 in the ₁ subunit is important for main-state conductances, while E290 and E297 in the subunit are involved in antagonism by picrotoxin. Phosphorylation (grey circles): In the ₁ subunit S391 is part of a consensus site for phosphorylation by protein kinase C. In the subunit, T363, T388 and Y413 form parts of consensus sites for phosphorylation by cAMP-dependent protein kinase, protein kinase C and tyrosine kinases, respectively. These sites flank the gephyrin-binding domain (amino acids 394–411; purple circles).

Figure 2. GlyR anchoring to the cytoskeleton. Heteromeric postsynaptic GlyRs consisting of (red) and (blue) subunits are linked to subsynaptic microtubules (grey) and microfilaments (black) via a gephyrin lattice (green).