Biochemical, Proteomic, Structural, and Thermodynamic Characterizations of Integrin-linked Kinase (ILK)
Bibliographic record
Abstract
Integrin-linked kinase (ILK) is one of the few evolutionarily conserved focal adhesion proteins involved in diverse cell adhesion-dependent physiological and pathological responses. Despite more than a decade of studies and extensive literature, the kinase function of ILK is controversial. ILK contains a highly degraded kinase active site but it has been argued that ILK may be an unusual manganese (Mn)-dependent serine-threonine kinase that targets specific substrates such as glycogen synthase kinase-3β (GSK-3β). In this study, we have tackled this issue by a systematic bottom-up biochemical, proteomic, structural, and thermodynamic analysis of ILK. We show that recombinant ILK from either bacteria or mammalian cells exhibits no kinase activity on GSK-3β in the presence of either Mn(2+) or the conventional kinase co-factor Mg(2+). A comprehensive and unbiased whole cell-based kinase assay using entire mammalian CG-4 and C2C12 cell lysate did not identify any specific ILK substrates. High resolution crystallographic structure analysis further confirmed that the Mn-bound ILK adopts the same pseudo active site conformation as that of the Mg-bound ILK. More importantly, thermodynamic analysis revealed that the K220M mutation, previously thought to inactivate ILK by disrupting ATP binding, significantly impairs the structural integrity and stability of ILK, which provides a new basis for understanding how this mutation caused renal agenesis, a failure of fetal kidney development. Collectively, our data provide strong evidence that ILK lacks intrinsic kinase function. It is a bona fide pseudokinase that likely evolved from an ancestral catalytic counterpart to act as a distinct scaffold to mediate protein-protein interactions during focal adhesion assembly and many other cellular events.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 teacher head, 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".