Cytochrome C1

Function

Cytochrome C1 plays a role in the electron transfer during oxidative phosphorylation. As an iron-sulfur protein approaches the b-c1 complex, it accepts an electron from the cytochrome b subunit, then undergoes a conformational change to attach to cytochrome c1. There, the electron carried by the iron-sulfur protein is transferred to the heme carried by cytochrome c1. This electron is then transferred to a heme carried by cytochrome c. This creates a reduced species of cytochrome c, which separates from the b-c1 complex and moves to the last enzyme in the electron transport chain, cytochrome c oxidase (Complex IV).

Species

CYC1 is a human gene that is conserved in chimpanzee, Rhesus monkey, dog, cow, mouse, rat, zebrafish, fruit fly, mosquito, C. elegans, S. cerevisiae, K. lactis, E. gossypii, S. pombe, N. crassa, A. thaliana, rice, and frog. There are orthologs of CYC1 in 137 known organisms.

In its structure and function, the cytochrome b-c1 complex bears extensive analogy to the cytochrome b6f complex of chloroplasts and cyanobacteria; cytochrome c1 plays an analogous role to cytochrome f, despite their different structures.

Clinical relevance

Mutations in the CYC1 gene are associated with mitochondrial complex III deficiency nuclear type 6. The disease symptoms include early childhood onset of severe lactic acidosis and ketoacidosis, usually in response to infection. Insulin-responsive hyperglycemia is also present, but psychomotor development appears normal. Mutation of CYC1 was observed to cause instability in the cytochrome b-c1 complex, which decreased its ability to create energy through oxidative phosphorylation. Mitochondrial complex III deficiency nuclear type 6 is autosomal recessive.

References

References

1. "CYC1 - Cytochrome c1, heme protein, mitochondrial precursor - Homo sapiens (Human) - CYC1 gene & protein".
2. (October 2010). "The binding interface of cytochrome c and cytochrome c₁ in the bc₁ complex: rationalizing the role of key residues". Biophysical Journal.
3. "CYC1 cytochrome c1 [Homo sapiens (human)]". U.S. National Library of Medicine.
4. "ortholog_gene_1537[group]". U.S. National Library of Medicine.
5. (June 1995). "Cytochrome f revealed". Trends in Biochemical Sciences.
6. {{OMIM. 123980. Cytochrome C!; CYC1
7. "OMIM Gene Map". Johns Hopkins University..