ArticleBlood2023
Mutations in atypical hemolytic uremic syndrome provide evidence for the role of calcium in complement factor I.
Article in Blood, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
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Who cites it
4 citing papers in PubMed.
- A young woman with membranoproliferative glomerulonephritis and persistent hypocomplementemia: a case report.BMC nephrology · 2026Article
- Post-transplant Thrombotic Microangiopathy.Journal of the American Society of Nephrology : JASN · 2025Review
- High disease activity correlate with decreased serum calcium in systemic lupus erythematosus.Scientific reports · 2025Article
- Functional evaluation of rare variants in complement factor I using a minigene assay.Frontiers in immunology · 2024Article
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4 authors.
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Abstract
Atypical hemolytic uremic syndrome (aHUS) is a rare thrombotic microangiopathy. Genetic variants in complement proteins are found in ≈60% of patients. Of these patients, ≈15% carry mutations in complement factor I (CFI). Factor I (FI) is a multidomain serine protease that cleaves and thereby inactivates C3b and C4b in the presence of cofactor proteins. Crystal structures have shown that FI possesses 2 calcium-binding domains, low-density lipoprotein receptor class A (LDLRA) 1 and LDLRA2. Yet, the role of calcium in FI is unknown. We determined that 9 genetic variants identified in aHUS (N151S, G162D, G188A, V230E, A240G, G243R, C247G, A258T, and Q260D) cluster around the calcium-binding site of LDLRA1. Using site-directed mutagenesis, we established that the synthesis of all, except A258T, was impaired, implying defective protein folding, perhaps due to loss of calcium binding. To further explore this possibility, we generated 12 alanine mutants that coordinate with the calcium in LDLRA1 and LDLRA2 (K239A, D242A, I244A, D246A, D252A, E253A, Y276A, N279A, E281A, D283A, D289A, and D290A) and are expected to perturb calcium binding. Except for K239A and Y276A, none of the mutants was secreted. These observations suggest that calcium ions play key structural and functional roles in FI.
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