LGALS9B

LGALS9B functions as a post-translational stabilizer of the eukaryotic translation elongation factor EEF1D in gastric cancer cells, where it competes with the E3 ubiquitin ligase HERC5 for binding to EEF1D and thereby blocks HERC5-mediated proteasomal degradation of EEF1D (PMID:39639171). The resulting accumulation of EEF1D drives activation of the PI3K/AKT signaling pathway, promoting cancer cell proliferation, migration, and invasion (PMID:39639171). Beyond this competitive-binding axis and its downstream signaling output, no further mechanistic detail for LGALS9B has been characterized in the available corpus.

1. 2024 Medium

   Established how LGALS9B controls EEF1D abundance: rather than acting catalytically, it physically competes with the E3 ligase HERC5 for EEF1D, answering whether the protein's effect is stabilizing and direct.

   Evidence Co-immunoprecipitation/binding competition assay with knockdown/overexpression and protein stability readouts, in vitro and in vivo

   PMID:39639171

   Open questions at the time

   • Single lab with limited orthogonal validation described
   • Binding interface and stoichiometry of LGALS9B-EEF1D-HERC5 competition not defined
   • Whether this mechanism operates outside gastric cancer cells is untested
2. 2024 Medium

   Connected the molecular stabilization event to a downstream phenotype, showing EEF1D enrichment activates PI3K/AKT signaling to drive malignant cell behaviors.

   Evidence Knockdown and overexpression with PI3K/AKT pathway activity readout and proliferation/migration/invasion assays, in vitro and in vivo

   PMID:39639171

   Open questions at the time

   • No independent replication reported
   • Mechanistic link between EEF1D level and PI3K/AKT activation not resolved at molecular level
   • Contribution of LGALS9B independent of the EEF1D axis unknown

• Whether LGALS9B has functions beyond EEF1D stabilization and any enzymatic or carbohydrate-binding activity remains uncharacterized in the available corpus.
• No structural model of the LGALS9B-EEF1D interaction
• No characterization of LGALS9B localization or expression regulation
• No data on additional binding partners or substrates