GNGT2 (Guanine nucleotide-binding protein G(t) subunit gamma-T2) is a protein subunit of the transducin complex in photoreceptor cells of the retina. It plays a vital role in phototransduction — the process that converts light signals into electrical impulses for the brain to interpret. By working with light-sensitive opsins, GNGT2 helps trigger the molecular changes necessary for vision.