SLC3A2 N‐glycosylation and alternate evolutionary trajectories for amino acid metabolism
Bibliographic record
Abstract
Cancer and other proliferative diseases are driven by cooperative rewiring of growth signaling and metabolism, where posttranslational modifications to proteins play a critical role in maintaining the disease state. Most PTMs require metabolites as donor substrates, providing underappreciated link between metabolism and signaling. Protein N‐glycosylation and Golgi remodeling of N‐glycan on receptor kinases, T cell receptor, glucagon receptor, and glucose transporters provides feedback between signaling and metabolism. In turn, N‐glycosylation requires uridine diphosphate N‐acetylglucosamine (UDP‐GlcNAc), generated by the hexosamine biosynthesis pathway (HBP) from glucose, glutamine and acetyl‐CoA, where the flux of these substrates into UDP‐GlcNAc are in competition with glycolysis, glutaminolysis and fatty‐acid turnover. Thus, N‐glycan branching, a pathway of N‐acetylglucosaminyltransferases (MGAT1, 2, 4 and 5, avian 6) in the Golgi, is a sensor of central metabolism. In a search for additional glycoproteins that link metabolism, N‐glycosylation and signaling, we identified SLC3A2 (4F2hc, CD98) , an adaptor to amino acid (AA) transporters SLC7A5‐11, ‐13 which stabilizes cell surface residency. The SLC3A2*SLC7A5 exchanger imports essential AA that stimulate mTOR signaling and anabolic metabolism, while SLC3A2*SLC7A11 supports glutathione synthesis and mitigation of oxidative stress. Analysis of SLC3A2 N‐glycans revealed stable site‐specific profiles of Golgi remodeling, with the exception of the conserved N365 where branching and poly‐N‐acetyllactosamine content were sensitive to the insertion of lost ancestral sites and to HBP. The N‐glycans are positioned to promote galectin‐mediated clustering with N‐glycosylated Na ++ /AA symporters and enhance diffusion‐limited flux between exchangers and AA /Na+ symporters. In a successful experiment of Nature, SLC3A2 has been deleted in Neoaves, a clade representing 95% of Ave species that are adapted for flapping flight, the most metabolically intense form of vertebrate locomotion. Neoaves have also acquired a unique N‐glycan branching specificity GnT‐VI (Mgat6, Q9DGD1), which may support an alternate clustering of N‐glycosylated transporters. KEAP1, and four SLC7A family exchangers are also absent, and two others have duplicated, consistent with a shift in metabolic imperatives of Neoaves. The fate of these genes in Primates, Neoaves and Naked mole rat highlights the tension between metabolic rates and oxidative stress that govern lifestyle and longevity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".