Cytochrome c1, heme protein, mitochondrial (CYC1), also known as UQCR4, MC3DN6, Complex III subunit 4, Cytochrome b-c1 complex subunit 4, or Ubiquinol-cytochrome-c reductase complex cytochrome c1 subunit is a protein that in humans is encoded by the CYC1gene. CYC1 is a respiratory subunit of Ubiquinol Cytochrome c Reductase (complex III), which is located in the inner mitochondrial membrane and is part of the electron transport chain. Mutations in this gene may cause mitochondrial complex III deficiency, nuclear, type 6.[5][6][7]
Variants of CYC1 have been associated with mitochondrial complex III deficiency, nuclear, type 6. Mitochondrial complex III deficiency, nuclear, type 6 is an autosomal recessive disorder of the mitochondrial respiratory chain resulting from a defect in Ubiquinol Cytochrome c Reductase (complex III) that leads to reduced complex III activity. Clinical features tend to emerge in early childhood and include episodic acute lactic acidosis, ketoacidosis, insulin-responsive hyperglycemia, liver dysfunction, encephalopathy, and associated infection, although psychomotor development may remain normal. Pathogenic mutations have included c.288G>T, p.Trp96Cys and c.643C>T p. Leu215Phe.[6][7][12]
Interactions
CYC1 has 78 protein-protein interactions with 72 of them being co-complex interactions.[13] CYC1 is one of 11 subunits of Ubiquinol Cytochrome c Reductase (b1-c complex) that includes the respiratory subunits cytochrome b, cytochrome c1 (CYC1), UQCRFS1, the core proteins UQCRC1 and UQCRC2, and the low-molecular weight proteins UQCRH, UQCRB, UQCRQ, UQCR10, UQCR11, as well as an additional cleavage product of UQCRFS1.[6][7] Additionally, CCP1, CDKA-1, and CDKB1-1 have also been found to interact with CYC1.[13]
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