D2 Dopamine Receptor Homodimerization Is Mediated by Multiple Sites of Interaction, Including an Intermolecular Interaction Involving Transmembrane Domain 4
Bibliographic record
Abstract
In this study, we examined the mechanisms of intermolecular interaction involved in D2 dopamine receptor dimer formation to develop an understanding of the quaternary structure of G protein-coupled receptors. The potential role of two mechanisms was investigated: disulfide bridges and hydrophobic interactions between transmembrane domains. D2 dopamine receptor oligomers were unaffected by treatment with a reducing agent; however, oligomers of the D1 dopamine receptor dissociated following a similar treatment. This observation suggested that other forces such as hydrophobic interactions were more robust in the D2 receptor than in the D1 receptor in maintaining oligomerization. To elucidate which transmembrane domains were involved in the intermolecular hydrophobic interactions, truncation mutants were generated by successive deletion of transmembrane domains from amino and/or carboxyl portions of the D2 dopamine receptor. Immunoblot analyses revealed that all the fragments were well expressed but only fragments containing transmembrane domain 4 were able to self-associate, suggesting that critical areas for receptor dimerization resided within this transmembrane domain. Disruption of the helical structure of transmembrane domain 4 in a truncated receptor capable of forming dimers interfered with its ability to self-associate; however, a similar disruption of the transmembrane domain 4 helix structure in the full-length receptor did not significantly affect dimerization. These results indicated that there are other sites of interaction involved in D2 receptor oligomer assembly in addition to transmembrane domain 4.
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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 | 0.000 | 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 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".