{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nAlthough the query specifically asks for a summary of SPANXA2-OT1 function, none of the provided abstracts mention or characterize SPANXA2-OT1. Instead, these studies focus on dissecting the roles of heterotrimeric G‐protein subunits in various physiological contexts. In several investigations, distinct G‑protein β and γ isoforms have been shown to contribute to receptor signaling in retinal cells as well as in systemic metabolic and cardiovascular regulation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn studies examining retinal function, one report demonstrated that Gγ13, together with selective Gβ subunits (notably Gβ3 and Gβ4), is preferentially expressed in ON bipolar cells where it colocalizes with metabotropic receptor components to mediate light‐induced signaling. Complementary work showed that deletion of Gβ3 leads to a diminished light response, mislocalization and downregulation of key cascade proteins, and even alterations in synaptic connectivity, thereby highlighting the importance of precise G‑protein subunit expression for robust phototransduction."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nOther investigations have extended the role of these G‑protein subunits beyond the retina. One study linked the duplication and consequent overexpression of the GNB3 gene to a syndrome marked by obesity, macrocephaly, intellectual disability, and seizures, while a separate analysis of GNB3‐null mice revealed effects on heart rate regulation without pronounced metabolic or blood pressure abnormalities. These findings collectively underscore the broader significance of G‑protein β subunit composition in systemic physiology, even though SPANXA2-OT1 remains unaddressed in these reports."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Liquan Huang, Marianna Max, Robert F Margolskee, et al. "}, {"type": "b", "children": [{"type": "t", "text": "G protein subunit G gamma 13 is coexpressed with G alpha o, G beta 3, and G beta 4 in retinal ON bipolar cells."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Comp Neurol (2003)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1002/cne.10396"}], "href": "https://doi.org/10.1002/cne.10396"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12454992"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12454992"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Anuradha Dhingra, Hariharasubramanian Ramakrishnan, Adam Neinstein, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Gβ3 is required for normal light ON responses and synaptic maintenance."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Neurosci (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1523/JNEUROSCI.1436-12.2012"}], "href": "https://doi.org/10.1523/JNEUROSCI.1436-12.2012"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "22895717"}], "href": "https://pubmed.ncbi.nlm.nih.gov/22895717"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Sergei S Nikonov, Arkady Lyubarsky, Marie E Fina, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Cones respond to light in the absence of transducin β subunit."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Neurosci (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1523/JNEUROSCI.5204-12.2013"}], "href": "https://doi.org/10.1523/JNEUROSCI.5204-12.2013"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23516284"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23516284"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Ian S Goldlust, Karen E Hermetz, Lisa M Catalano, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Mouse model implicates GNB3 duplication in a childhood obesity syndrome."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Proc Natl Acad Sci U S A (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1073/pnas.1305999110"}], "href": "https://doi.org/10.1073/pnas.1305999110"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23980137"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23980137"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Yuanchao Ye, Zhizeng Sun, Ang Guo, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Ablation of the GNB3 gene in mice does not affect body weight, metabolism or blood pressure, but causes bradycardia."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Cell Signal (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.cellsig.2014.07.030"}], "href": "https://doi.org/10.1016/j.cellsig.2014.07.030"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25093805"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25093805"}]}]}]}