Functions as signal transducer for the rod photoreceptor RHO (PubMed:21285355, PubMed:23303210, PubMed:28655769, PubMed:8259210). Required for normal RHO-mediated light perception by the retina (By similarity). Guanine nucleotide-binding proteins (G proteins) function as transducers downstream of G protein-coupled receptors (GPCRs), such as the photoreceptor RHO. The alpha chain contains the guanine nucleotide binding site and alternates between an active, GTP-bound state and an inactive, GDP-bound state (PubMed:21285355, PubMed:28655769, PubMed:8259210, PubMed:8208289, PubMed:7969474). Activated RHO promotes GDP release and GTP binding (PubMed:21285355, PubMed:28655769). Signaling is mediated via downstream effector proteins, such as cGMP-phosphodiesterase (PubMed:21285355). Heterotrimeric G proteins are composed of 3 subunits alpha, beta and gamma (PubMed:21285355, PubMed:23303210, PubMed:28655769). The alpha chain contains the guanine nucleotide binding site (PubMed:21285355, PubMed:8259210, PubMed:8208289, PubMed:7969474). Interacts with RHO (PubMed:21285355, PubMed:23303210, PubMed:28655769, PubMed:9539726, PubMed:21389983, PubMed:23579341, PubMed:21389988, PubMed:18818650). Interacts with RGS9 and PDE6G (PubMed:11234020). Interacts (when myristoylated) with UNC119; interaction is required for localization in sensory neurons (By similarity). Localizes mainly in the outer segment in the dark-adapted state, whereas is translocated to the inner part of the photoreceptors in the light-adapted state. During dark-adapted conditions, in the presence of UNC119 mislocalizes from the outer segment to the inner part of rod photoreceptors which leads to decreased photoreceptor damage caused by light. Rod.