<i>In Situ</i>Visualization of Protein Interactions in Sensory Neurons: Glutamic Acid-Rich Proteins (GARPs) Play Differential Roles for Photoreceptor Outer Segment Scaffolding
Bibliographic record
Abstract
Vertebrate photoreceptors initiate vision via a G-protein-mediated signaling cascade organized within a specialized cilium, the outer segment (OS). The membranous "stacked pancake" architecture of this organelle must be partially renewed daily to maintain cell function and viability; however, neither its static structure nor renewal process is well described in molecular terms. Glutamic acid-rich proteins (GARPs), including the cyclic nucleotide-gated cation channel (CNGB1) and GARP2 (a CNGB1 splice-variant), are proposed to contribute to OS organization in concert with peripherin/rds (P/rds), a retinal tetraspanin. We developed and applied an in situ fluorescence complementation approach that offers an unprecedented glimpse at the formation, trafficking, and localization of GARP-P/rds interactions in transgenic Xenopus laevis rod photoreceptors. Interactions for these (and other) proteins could be readily visualized using confocal microscopy. Nearly all associations, including CNGB1-P/rds interaction, were initiated within inner segments (ISs) before trafficking to OSs. In contrast, GARP2-P/rds interactions were only observed downstream, at or near sites of disk morphogenesis. These results suggest that GARP2-P/rds interaction participates directly in structuring disk stacks but CNGB1-P/rds interaction does not and instead serves mainly to localize plasma membrane ion channels. Altogether, the results lead us to propose that differential interaction of GARPs with P/rds may contribute to the broad phenotypic heterogeneity produced by inherited defects in P/rds. Analogous experiments applied to the synaptic protein RIBEYE suggest that monomers can oligomerize at the level of the IS before ribbon assembly and demonstrate the general applicability of this strategy for in situ analysis of protein interactions in sensory neurons.
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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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".