{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n GRIFIN is a lens‐enriched protein that, although structurally related to galectins, exhibits unique features that suggest a specialized role in the ocular lens. Initial studies identified GRIFIN as a highly abundant, soluble protein localized at the interfaces between lens fiber cells, with characteristics consistent with a crystallin‐like function even though its carbohydrate‐binding domain has diverged; for example, in some species it retains β‐galactoside binding while in others (notably mammals) key residues have been altered, which may modulate its lectin activity."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Structural and biophysical analyses reveal that GRIFIN forms a compact, stable homodimer and, in avian lenses, demonstrates canonical binding to lactose with only subtle deviations that are overcome by minor side‐chain adjustments. Furthermore, its gene expression appears strictly confined to the lens where it is developmentally regulated by key transcription factors such as L‐Maf and Pax6, highlighting its contribution to lens differentiation and the precise organization of fiber cells."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition to its structural role, GRIFIN has been identified as a binding partner of α‐crystallin. Cross‐linking and binding assays demonstrate that α‐crystallin interacts with GRIFIN with reasonably high affinity, an association that is further enhanced in the presence of ATP. This interaction suggests that GRIFIN may help modulate the chaperone activity or the assembly state of crystallin complexes, thereby contributing to the maintenance of lens transparency and proper refractive properties."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In summary, the collective evidence supports a model in which GRIFIN functions as a novel, lens‐specific crystallin. Through its interactions with other crystallins and its regulated expression during lens fiber cell differentiation, GRIFIN likely participates in ensuring the highly ordered architecture of the lens required for optimal optical function.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "A T Ogden, I Nunes, K Ko, et al. "}, {"type": "b", "children": [{"type": "t", "text": "GRIFIN, a novel lens-specific protein related to the galectin family."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (1998)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.273.44.28889"}], "href": "https://doi.org/10.1074/jbc.273.44.28889"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "9786891"}], "href": "https://pubmed.ncbi.nlm.nih.gov/9786891"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Federico M Ruiz, Ulrich Gilles, Anna-Kristin Ludwig, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Chicken GRIFIN: Structural characterization in crystals and in solution."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochimie (2018)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.biochi.2017.12.003"}], "href": "https://doi.org/10.1016/j.biochi.2017.12.003"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "29248541"}], "href": "https://pubmed.ncbi.nlm.nih.gov/29248541"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Gabriel García Caballero, Herbert Kaltner, Malwina Michalak, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Chicken GRIFIN: A homodimeric member of the galectin network with canonical properties and a unique expression profile."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochimie (2016)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.biochi.2016.06.001"}], "href": "https://doi.org/10.1016/j.biochi.2016.06.001"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "27296808"}], "href": "https://pubmed.ncbi.nlm.nih.gov/27296808"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Gabriel García Caballero, Sebastian Schmidt, Martina Schnölzer, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Chicken GRIFIN: binding partners, developmental course of localization and activation of its lens-specific gene expression by L-Maf/Pax6."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Cell Tissue Res (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s00441-018-2931-x"}], "href": "https://doi.org/10.1007/s00441-018-2931-x"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "30328540"}], "href": "https://pubmed.ncbi.nlm.nih.gov/30328540"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Kelly A Barton, Cheng-Da Hsu, J Mark Petrash "}, {"type": "b", "children": [{"type": "t", "text": "Interactions between small heat shock protein alpha-crystallin and galectin-related interfiber protein (GRIFIN) in the ocular lens."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochemistry (2009)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1021/bi802203a"}], "href": "https://doi.org/10.1021/bi802203a"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "19296714"}], "href": "https://pubmed.ncbi.nlm.nih.gov/19296714"}]}]}]}