Abstract: C1r is a modular serine protease present in the serum C1 complex. It forms a homodimer of 173 kDa and is mainly associated with the homologous C1s protease in a calcium-dependent manner. Expression of the C1r and C1s proteases is coordinated in hepatocytes. Their main known function is activation of the classical complement pathway, a crucial innate immune defence mechanism. This tightly controlled process needs first activation of C1r, which is triggered when the C1 complex binds to an activating target. This activation is mediated by the cleavage of a single Arg–Ile bond, which triggers a conformational transition towards the active state. Structures of the C1r catalytic domain have been determined in both the proenzyme and activated states. C1r complete deficiencies are rare and often associated with pyogenic infections and autoimmune diseases such as systemic lupus erythematosus. Some heterozygous C1r mutations have been linked to periodontal Ehlers-Danlos syndrome.
Publication Year: 2018
Publication Date: 2018-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 1
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