| Aspect | Key mechanistic/biological fact for human AIPL1 (UniProt Q9NZN9) | Best supporting citation IDs |
|---|---|---|
| Verified identity | AIPL1 is the human aryl-hydrocarbon-interacting protein-like 1, a 384-aa retina-enriched photoreceptor protein with FKBP-like, TPR, and C-terminal proline-rich features consistent with UniProt Q9NZN9. | (pqac-00000005, pqac-00000006) |
| Domain architecture | Domain organization comprises an N-terminal FKBP-like domain, an insert region within/adjacent to the FKBP-like module, three TPR repeats, and a primate-specific C-terminal proline-rich domain (PRD). Reported residue mapping includes FKBP 12–157, TPR1 178–213, TPR2 219–260, TPR3 264–297, PRD 328–384. | (pqac-00000005, pqac-00000006) |
| HSP90 interaction | The TPR domain is required for HSP90 binding, while FKBP-like domain features contribute to the HSP90-associated co-chaperone interface; AIPL1 preferentially binds the closed ATP-bound HSP90 dimer and forms an HSP90-dependent complex needed for PDE6 maturation. | (pqac-00000001, pqac-00000002) |
| PDE6 client relationship | AIPL1 is an obligate/specialized photoreceptor co-chaperone for rod and cone PDE6, promoting PDE6 folding, holoenzyme assembly, maturation, and stability before delivery to outer segments. Loss of AIPL1 causes rapid PDE6 loss and downstream cGMP dysregulation. | (pqac-00000002, pqac-00000008, pqac-00000014) |
| Prenyl/farnesyl recognition | AIPL1 preferentially binds prenylated PDE6 subunits through its FKBP-like domain; PDE6 prenylation is required for productive AIPL1 binding, especially the farnesylated PDE6A subunit, and is important for stable AIPL1–HSP90–PDE6 ternary complex formation. | (pqac-00000006, pqac-00000008, pqac-00000010) |
| Major binding partners | Best-supported interactors include HSP90/HSP70, PDE6 catalytic and regulatory subunits, FAT10, and NUB1. FAT10 binds AIPL1 TPR motifs; NUB1 binds within residues ~181–330; these interactions connect AIPL1 to PDE6 proteostasis. | (pqac-00000001, pqac-00000002, pqac-00000028) |
| FAT10/NUB1 proteostasis axis | Beyond PDE6 maturation, AIPL1 stabilizes FAT10 and PDE6β–FAT10 conjugates and is proposed to oppose NUB1/FAT10-linked proteasomal loss of PDE6. FAT10 both inhibits PDE6 cGMP hydrolysis non-covalently and targets FAT10ylated PDE6 for proteasomal degradation. | (pqac-00000022, pqac-00000023, pqac-00000025) |
| Subcellular localization | Evidence places AIPL1 mainly in photoreceptor inner segments and connecting cilium/ciliary region, supporting a principal role in PDE6 maturation rather than direct outer-segment trafficking. Adult human retina data show strongest expression in rods, with developmental expression in both rods and cones. | (pqac-00000003, pqac-00000005, pqac-00000008) |
| Rods versus cones | In adult human retina, immunofluorescence detects AIPL1 mainly in rods, whereas developmental studies and organoid/transcript data indicate expression in both rods and developing cones, later reduced in mature cones. AIPL1 is nevertheless important for cone viability/function. | (pqac-00000003, pqac-00000005) |
| Primary biological role | AIPL1 is not an enzyme or transporter; its primary role is a photoreceptor-specific HSP90-dependent co-chaperone/adaptor that recognizes prenylated PDE6 and enables correct folding, assembly, and maintenance of the visual effector phosphodiesterase required for phototransduction. | (pqac-00000001, pqac-00000008, pqac-00000013) |
| Disease association | Biallelic loss-of-function AIPL1 variants cause autosomal recessive LCA4/early-onset severe retinal dystrophy, typically with severe infantile visual impairment and rapid rod-cone degeneration. Reviews cite AIPL1 among the more severe LCA genes, with genotype–severity variation. | (pqac-00000008, pqac-00000014) |
| Recent cohort statistics | In a 2024 cohort of 52 children with LCA, AIPL1 variants were identified in 4/52 patients (7.7%); recurrent AIPL1 c.421C>T (p.Q141X) was observed in four non-consanguineous patients. The AIPL1 subgroup had mean age 2.8 ± 1.7 years and onset 5.5 ± 2.1 months. | (pqac-00000030, pqac-00000031) |
| Preclinical gene therapy | In 2024 human iPSC-derived retinal organoids modeling AIPL1-LCA4, AAV7m8.hRKp.AIPL1 restored AIPL1 expression, rescued rod PDE6, and normalized elevated cGMP. Rescue was detectable by 14 days and sustained up to 70 days in reported experiments. | (pqac-00000015, pqac-00000016, pqac-00000017) |
| Quantitative organoid rescue notes | After AAV treatment, AIPL1-positive cells were detected in a minority of rods/cones (roughly ~11–15% of marker-positive photoreceptors depending on model/time point), yet this was sufficient to rescue PDE6 and reduce cGMP to control-like levels in organoids. | (pqac-00000017, pqac-00000020) |
| Clinical translation | A clinical study is underway for AIPL1-IRD: NCT07063030 (“A Study of LX107 Gene Therapy in AIPL1-IRD Patients”), an early phase 1, recruiting, single-group trial in Shanghai testing single subretinal LX107 administration in patients with biallelic AIPL1 mutations; primary endpoint is safety over 6 months. | (pqac-00000035) |


*Table: This table condenses the most important mechanistic, localization, disease, and therapeutic facts about human AIPL1, with direct context-ID citations for each point. It is useful as a quick-reference evidence map linking AIPL1 biology to PDE6 maturation and current translational work.*