| Biological role/process | Mechanism (molecular events) | Key partners/effectors | Subcellular/tissue localization | Key evidence (with brief quantitative detail where available) | Key citations |
|---|---|---|---|---|---|
| Canonical circadian photoreception and clock entrainment | Blue light is absorbed by FAD in DmCRY, driving photoreduction via the Trp tetrad/triad and release of the autoinhibitory C-terminal tail (CTT). Light-state CRY then binds TIM; JET/CUL1 promotes TIM ubiquitination/proteasomal degradation, while BRWD3/Ramshackle-CUL4 contributes to CRY ubiquitination/self-degradation. | FAD, TIM, JET, CUL1, BRWD3/Ramshackle, proteasome | Clock neurons; nuclear and cytoplasmic pools reported, with nuclear CRY implicated in TIM degradation | CRY:TIM cryo-EM map reached 3.3 Å; primary interface buries ~1862 Ų on TIM and ~1807 Ų on CRY; TIM ARM1 helix replaces the CRY CTT in the flavin pocket; WT CRY binds TIM more strongly in light than dark (KD ~9 µM light vs ~32 µM dark), whereas CTT-deleted CRY binds constitutively (KD ~1.7 µM) (pqac-00000035, pqac-00000039, pqac-00000011, pqac-00000008) | (pqac-00000003, pqac-00000008, pqac-00000009, pqac-00000011, pqac-00000013, pqac-00000035, pqac-00000039) |
| Structural basis of light-gated TIM recognition | TIM inserts an N-terminal helix into the CRY flavin pocket; CRY phosphate-binding loop (PBL), protrusion motif, C-terminal lid, and Arg residues rearrange around FAD to stabilize the signaling state. Histidines H377/H378 help couple FAD redox chemistry to TIM binding. | TIM ARM repeats, TIM N-terminus, FAD, H377, H378, Arg237/Arg258, PBL | CRY photolyase homology region/flavin pocket | TIM-bound CRY shows FAD adenine shift ~1.5 Å; Arg258 replaces a coordinating Mg2+ at the diphosphate region; local density supported TIM insertion at up to ~2.4 Å local resolution; H377L stabilizes TIM-binding conformation and increases TIM binding in pulldown/SWFTI assays (pqac-00000036, pqac-00000037, pqac-00000038) | (pqac-00000006, pqac-00000009, pqac-00000010, pqac-00000014, pqac-00000034, pqac-00000036, pqac-00000037, pqac-00000038) |
| Cofactor-dependent folding/biogenesis | dCRY folds through multiple intermediates; early folding steps are FAD-independent, but later steps require FAD binding to largely unfolded intermediates to reach the native signaling-competent state. | FAD, folding intermediates I1/I2/I3, PHR/CTT regions | Intracellular newly synthesized dCRY protein | Single-molecule analysis resolved five states; FAD association rates were extremely fast, k3 ≈ 2.8×10^9 M^-1 s^-1 and k4 ≈ 1.0×10^10 M^-1 s^-1, with sub-nanomolar dissociation constants (~0.25–0.29 nM); at 10 nM FAD the average folding time was ~30 s and folding probability by 40 s was ~0.73 (pqac-00000046, pqac-00000049) | (pqac-00000046, pqac-00000047, pqac-00000048, pqac-00000049, pqac-00000051) |
| Non-canonical neuronal photoreception: arousal and rapid membrane depolarization | Light-activated/redox-switched CRY modulates Kvβ-associated potassium-channel signaling, promoting membrane depolarization and firing in light-responsive arousal neurons independently of the canonical TIM-degradation mechanism. | Hyperkinetic (HK/Kvβ), EAG/ERG/Shaker-family K+ channel complexes, flavin redox chemistry | Large ventrolateral neurons (l-LNvs) and other CRY-positive central brain neurons | Reviews and recent analyses place CRY in light-activated arousal neurons; l-LNv photoresponses require potassium-channel modulation and flavin redox chemistry; cry mutants show defective blue/UV-light arousal and UV avoidance phenotypes (pqac-00000023, pqac-00000024, pqac-00000028) | (pqac-00000023, pqac-00000024, pqac-00000028) |
| Eye structural/signaling role: actin/signalplex organization and enhanced circadian photosensitivity | In rhabdomeres, CRY acts as a structural/assembling factor rather than a degradable clock photoreceptor pool; it binds F-actin and light-dependently interacts with the scaffold INAD to help maintain the phototransduction signalplex near the membrane, thereby enhancing eye-mediated clock light input. | F-actin, INAD, NINAC/myosin III, TRP channels, phototransduction signalplex | Compound-eye photoreceptor rhabdomeres and photoreceptor cell bodies | Rhabdomeric CRY staining was unchanged after 2 h of 1000 lux light (p = 0.404) and unchanged between ZT23 and ZT11 (p = 1.0), whereas somatic CRY was lower at ZT11 than ZT23 (p < 0.001); rhabdomeric signal never exceeded mean pixel gray ~25, while somatic signal reached ~40 after prolonged darkness (pqac-00000017, pqac-00000018, pqac-00000041) | (pqac-00000016, pqac-00000017, pqac-00000018, pqac-00000019, pqac-00000022, pqac-00000041) |
| Magnetosensitivity / magnetic-field-dependent behavior | CRY photochemistry has been proposed to generate radical-pair states after light activation, linking blue/UV light sensing to magnetic-field effects on neuronal signaling and behavior. | FAD radical states, Trp electron-transfer chain, possible superoxide/radical-pair intermediates | CRY-expressing neurons; behavioral output circuits | Reviews summarize that cry mutants lose magnetic-field-dependent learning/behavioral effects and that human CRY2 can rescue some fly magnetic phenotypes; magnetic effects also alter geotaxis/locomotion and seizure-like responses under blue/UV light (pqac-00000023, pqac-00000025, pqac-00000027) | (pqac-00000023, pqac-00000025, pqac-00000027) |
| Metabolic regulation: triglyceride storage, starvation resistance, feeding, lifespan | Beyond light resetting, CRY influences metabolic state and diet-responsive triglyceride utilization, likely through circadian/metabolic coupling rather than a simple acute phototransduction effect. | Circadian clock network, triglyceride/glycogen metabolism pathways, diet-response pathways | Metabolically active tissues including gut and fat body; also peripheral clocks | In cry01 mutants, starvation resistance and TG levels increased under LD and LL; TG remained significantly higher than controls at 12, 15, 18, and 24 h post-starvation (P < 0.0001); median time to 50% death increased to 70.66 ± 1.82 d in cry01 vs 40.03 ± 1.44 d in w1118 (P < 0.001) (pqac-00000032, pqac-00000033) | (pqac-00000029, pqac-00000032, pqac-00000033) |
| Light-independent modulation of clock amplitude/peripheral clocks | CRY can support molecular rhythm amplitude and peripheral-clock function even outside acute TIM degradation, and can contribute to repression mechanisms in some tissues/contexts. | PER, CLK/CYC, peripheral-clock components | Malpighian tubules, eye, antennae, other peripheral tissues | Reviews summarize tissue-specific light sensitivity and light-independent CRY roles in maintaining oscillation amplitude/peripheral rhythms; effects are context dependent rather than universal across all tissues (pqac-00000024, pqac-00000026, pqac-00000029) | (pqac-00000024, pqac-00000026, pqac-00000029) |


*Table: This table summarizes the best-supported functional annotation for Drosophila melanogaster Cryptochrome-1 (cry; UniProt O77059), covering canonical circadian entrainment and major non-canonical roles. It highlights mechanisms, partners, localization, and quantitative findings useful for narrative gene-function annotation.*