Heparin Cofactor II: Discovery, Properties, and Role in Controlling Vascular Homeostasis
Bibliographic record
Abstract
Heparin cofactor II (HCII) is a serine protease inhibitor (serpin) found in high concentrations in human plasma. Despite its discovery >30 years ago, its physiological function is still poorly understood. It is known to inhibit thrombin, the predominant coagulation protease, and HCII-thrombin complexes have been found in plasma, yet it is thought to contribute little to normal hemostasis. However, thrombin has several other physiological functions, and therefore many biological roles for HCII need consideration. The unique structure and mechanism of action of HCII have helped guide our understanding of HCII. In particular, HCII binds many glycosaminoglycans (GAGs) such as heparin and heparin sulfate as well as several different polyanions to enhance its inhibition of thrombin. Distinctly, HCII is able to use the GAG dermatan sulfate for accelerated thrombin inhibition. Dermatan sulfate is found in high concentrations in the walls of blood vessels as well as in placental tissue. This knowledge has led to research indicating that HCII may play a protective role in atherosclerosis and placental thrombosis. Additionally, pharmaceuticals are being developed that use the dermatan sulfate activation of HCII for anticoagulation. Although much research is still needed to fully understand HCII, this humble protein may have significant impact in our medical future. This article reviews the laboratory history, protein characteristics, structure-activity relationships, protease inhibition, physiological function, and medical relevance of HCII in hopes of regenerating interest in this sometimes forgotten serpin.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".