| Function Category | Specific Function | Molecular Mechanism | Evidence/Key Findings | Citations |
|---|---|---|---|---|
| GTPase activity | DRG2 is a TRAFAC/OBG-family guanine nucleotide hydrolase | Binds GTP through a canonical G domain with conserved G1-G5 motifs and hydrolyzes GTP to GDP; like other DRGs, functions through the GTPase cycle and does not appear to require classical GAPs or GEFs | Reviews of DRG proteins place human DRG2 in the OBG/HflX-like TRAFAC GTPase family and describe conserved G-domain architecture and intrinsic GTP hydrolysis as core biochemical activity (pqac-00000004, pqac-00000008, pqac-00000010) | (pqac-00000004, pqac-00000008, pqac-00000010) |
| GTPase activity | Substrate specificity: guanine nucleotides, especially GTP | The catalytic substrate is GTP; hydrolysis generates GDP + Pi, consistent with the canonical molecular-switch mechanism of TRAFAC GTPases | DRG1/2 are described as GTP-binding proteins with conserved G motifs; reviews explicitly define DRGs as GTPases cycling between GTP-bound and GDP-bound states (pqac-00000004, pqac-00000010) | (pqac-00000004, pqac-00000010) |
| GTPase activity | Potassium-responsive intrinsic activity is inferred for DRG2 from close paralogy with DRG1 | DRG1 has potassium-dependent intrinsic GTPase activity, and the high sequence similarity between DRG1 and DRG2 suggests analogous regulation, though direct biochemical confirmation for DRG2 remains limited | Review literature states DRG1 GTPase activity is strongly stimulated by potassium and notes DRG2 likely behaves similarly because of high sequence conservation, but stops short of direct proof for DRG2 (pqac-00000006, pqac-00000017) | (pqac-00000006, pqac-00000017) |
| GTPase activity regulation | Regulation by DFRP2/RWDD1 | DRG2 forms a specific obligate heterodimer with DFRP2; DFRP2 stabilizes DRG2 protein and is thought to be required for normal function, though unlike DFRP1-DRG1, stimulation of GTPase activity has not been demonstrated for DFRP2 | Endogenous and overexpression studies show strict DRG2-DFRP2 pairing; DFRP binding prevents DRG degradation. A 2024 preprint specifically reports that DFRP1 stimulates DRG1 GTPase activity whereas DFRP2 binding does not stimulate DRG1, underscoring functional divergence among paralogous complexes (pqac-00000001, pqac-00000011, pqac-00000017) | (pqac-00000001, pqac-00000011, pqac-00000017) |
| Translation function | General translation factor promoting protein synthesis under ribosome pausing/stalling | DRG proteins act on stalled/paused ribosomes to enhance productive translation rather than defaulting to quality-control disposal | 2024 studies propose DRG proteins as a new class of general translation factors that promote protein biosynthesis in halted ribosomes across evolution; rescue of growth/translation defects in DRG-deficient yeast and human cells supports a conserved role (pqac-00000000, pqac-00000002, pqac-00000009, pqac-00000012) | (pqac-00000000, pqac-00000002, pqac-00000009, pqac-00000012) |
| Translation function | Ribosome binding during elongation stress/collision | DRG2/DFRP2 is proposed to associate with collided or slowly elongating ribosomes, potentially via DFRP2-dependent recruitment mechanisms distinct from DRG1/DFRP1 | Recent structural/functional synthesis states DRG2/DFRP2 may bind collided ribosomes together with Gcn1, with the DFRP2 RWD domain implicated in this pathway; DRG/DFRP complexes are repeatedly linked to elongation control on slow or stalled ribosomes (pqac-00000011, pqac-00000017) | (pqac-00000011, pqac-00000017) |
| Translation function | Promotion of peptidyl transfer and stall resolution | GTP-bound DRG/Obg-like proteins enhance ribosome catalytic activity, likely by stimulating peptidyl transfer, thereby helping paused ribosomes resume productive elongation | 2024 DRG/Obg work reports that Obg-GTP stimulates peptidyl transfer, the key catalytic function of the ribosome, and that DRG proteins alleviate anisomycin- or poly(A)-induced translational stalling in yeast and human cells (pqac-00000000, pqac-00000002, pqac-00000009, pqac-00000012) | (pqac-00000000, pqac-00000002, pqac-00000009, pqac-00000012) |
| Translation function | Requirement for GTPase activity in translation-associated cellular function | Catalytic competence of the G domain is necessary for ribosome-associated function | Mutations in the conserved G1 motif that impair GTP hydrolysis abolish functional rescue and reduce ribosome association in yeast ortholog studies, supporting a conserved requirement for GTPase activity in DRG-mediated translation control (pqac-00000009, pqac-00000012) | (pqac-00000009, pqac-00000012) |
| Post-translational modification | JMJD7-mediated (3S)-lysyl hydroxylation of DRG2 | JMJD7, a 2-oxoglutarate/Fe(II)-dependent oxygenase, hydroxylates a conserved lysine in the N-terminal HTH region of DRG2 (K21) | Proteomics, cellular co-IP, MS, and peptide assays identified DRG1/2 as JMJD7 substrates and mapped hydroxylation to the conserved N-terminal lysine; JMJD7 and DRG2 co-localize in nuclear and cytoplasmic compartments (pqac-00000003, pqac-00000007) | (pqac-00000003, pqac-00000007) |
| Post-translational modification | Functional effect of DRG2 hydroxylation: enhanced RNA interaction rather than altered stability or GTPase activity | The hydroxylated lysine lies in the HTH domain and promotes RNA binding; available data did not show major effects on DRG stability, DFRP binding, or GTPase activity | JMJD7 depletion reduced DRG2 RNA-binding affinity, while hydroxylation-site mutation also impaired RNA interaction; the same study found no consistent change in DRG expression, thermal stability, DFRP association, or GTPase activity (pqac-00000013) | (pqac-00000013) |
| Endosomal trafficking | Regulation of Rab5-positive early endosome function | DRG2 localizes to Rab5-containing early endosomes and promotes Rab5 deactivation, a step needed for endosomal maturation and recycling | Prior work summarized in the 2024 melanoma study states that DRG2 interacts with Rab5 on early endosomes; DRG2 loss causes defects in Rab5 deactivation and endosomal recycling (pqac-00000005, pqac-00000014, pqac-00000016) | (pqac-00000005, pqac-00000014, pqac-00000016) |
| Endosomal trafficking | Control of receptor recycling, including PD-L1 and transferrin receptor | By supporting endosomal recycling, DRG2 helps return internalized cargo from endosomes to the plasma membrane; depletion traps cargo intracellularly | The 2024 cancer study reports that DRG2 deficiency impairs recycling of endosomal PD-L1 and lowers its surface abundance despite increased total PD-L1; prior work cited there also linked DRG2 loss to delayed transferrin receptor recycling and altered EGFR trafficking (pqac-00000005, pqac-00000014, pqac-00000016) | (pqac-00000005, pqac-00000014, pqac-00000016) |
| Endosomal trafficking / immunobiology | Support of tumor-cell surface PD-L1 localization and anti-PD-1 response | DRG2 promotes recycling of internalized PD-L1 back to the plasma membrane, enabling productive PD-L1:PD-1 interaction | In melanoma models, DRG2 depletion reduced surface PD-L1, impaired PD-1 binding, prevented anti-PD-1-induced expansion of effector-like T cells, and was associated with resistance to anti-PD-1 therapy in patient cohort analysis (pqac-00000005, pqac-00000014) | (pqac-00000005, pqac-00000014) |


*Table: This table summarizes the main experimentally supported molecular functions of human DRG2, emphasizing its GTPase activity, translation-related role on stalled ribosomes, JMJD7-mediated hydroxylation, and endosomal trafficking functions. It is useful for quickly separating firmly supported findings from mechanistic inferences, especially where DRG2 evidence is extrapolated from the closely related DRG1 paralog.*