HCCS (gene)

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Identifiers
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External IDs	GeneCards: [1]
Orthologs
Species	Human	Mouse
Entrez	n/a	n/a
Ensembl	n/a	n/a
UniProt	n/a	n/a
RefSeq (mRNA)	n/a	n/a
RefSeq (protein)	n/a	n/a
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Wikidata
View/Edit Human

Cytochrome c-type heme lyase is an enzyme that in humans is encoded by the HCCS gene on chromosome X.

Structure

The HCCS gene is located on the Xp22 region of chromosome X and encodes a protein that is ~30 kDa in size. The HCCS protein is localized to the inner mitochondrial membrane and is expressed in multiple tissue including prominently in the cardiovascular system and the central nervous system.

Function

The HCCS protein functions as a lyase to covalently attach the heme group to the apoprotein of cytochrome c on the inner mitochondrial membrane of the mitochondrion. The heme group is required for cytochrome c to transport electrons from complex III to complex IV of the electron transport chain during respiration. Heme attachment to cytochrome c takes place in the intermembrane space and requires conserved heme-interacting residues on HCCS on one of the two heme-binding domains on HCCS, including His154. The HCCS protein may function to regulate mitochondrial lipid and total mitochondrial mass in response to mitochondrial dysfunctions.

Clinical Significance

Mutations in the MCCS gene cause Microphthalmia with linear skin defects (MLS) syndrome, also known as MIDAS syndrome, microphthalmia, syndromic 7 (MCOPS7), or microphthalmia, dermal aplasia, and sclerocornea. MLS is a rare X-linked dominant male-lethal disease characterized by unilateral or bilateral microphthalmia and linear skin defects in affected females, and in utero lethality for affected males.

Further reading

• Wapenaar MC, Bassi MT, Schaefer L, et al. (1993). "The genes for X-linked ocular albinism (OA1) and microphthalmia with linear skin defects (MLS): cloning and characterization of the critical regions". Hum. Mol. Genet. 2 (7): 947–52. doi:10.1093/hmg/2.7.947. PMID 8364577.
• Schaefer L, Ballabio A, Zoghbi HY (1997). "Cloning and characterization of a putative human holocytochrome c-type synthetase gene (HCCS) isolated from the critical region for microphthalmia with linear skin defects (MLS)". Genomics. 34 (2): 166–72. doi:10.1006/geno.1996.0261. PMID 8661044.
• Van den Veyver IB, Subramanian S, Zoghbi HY (1998). "Genomic structure of a human holocytochrome c-type synthetase gene in Xp22.3 and mutation analysis in patients with Rett syndrome". Am. J. Med. Genet. 78 (2): 179–81. doi:10.1002/(SICI)1096-8628(19980630)78:2<179::AID-AJMG17>3.0.CO;2-K. PMID 9674913.
• Schwarz QP, Cox TC (2002). "Complementation of a yeast CYC3 deficiency identifies an X-linked mammalian activator of apocytochrome c". Genomics. 79 (1): 51–7. doi:10.1006/geno.2001.6677. PMID 11827457.
• Prakash SK, Cormier TA, McCall AE, et al. (2003). "Loss of holocytochrome c-type synthetase causes the male lethality of X-linked dominant microphthalmia with linear skin defects (MLS) syndrome". Hum. Mol. Genet. 11 (25): 3237–48. doi:10.1093/hmg/11.25.3237. PMID 12444108.
• Strausberg RL, Feingold EA, Grouse LH, et al. (2003). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. doi:10.1073/pnas.242603899. PMC 139241. PMID 12477932.
• Ota T, Suzuki Y, Nishikawa T, et al. (2004). "Complete sequencing and characterization of 21,243 full-length human cDNAs". Nat. Genet. 36 (1): 40–5. doi:10.1038/ng1285. PMID 14702039.
• Gerhard DS, Wagner L, Feingold EA, et al. (2004). "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)". Genome Res. 14 (10B): 2121–7. doi:10.1101/gr.2596504. PMC 528928. PMID 15489334.
• Nakashima-Kamimura N, Asoh S, Ishibashi Y, et al. (2006). "MIDAS/GPP34, a nuclear gene product, regulates total mitochondrial mass in response to mitochondrial dysfunction". J. Cell Sci. 118 (Pt 22): 5357–67. doi:10.1242/jcs.02645. PMID 16263763.
• Wimplinger I, Morleo M, Rosenberger G, et al. (2006). "Mutations of the mitochondrial holocytochrome c-type synthase in X-linked dominant microphthalmia with linear skin defects syndrome". Am. J. Hum. Genet. 79 (5): 878–89. doi:10.1086/508474. PMC 1698567. PMID 17033964.
• Wimplinger I, Shaw GM, Kutsche K (2007). "HCCS loss-of-function missense mutation in a female with bilateral microphthalmia and sclerocornea: a novel gene for severe ocular malformations?". Mol. Vis. 13: 1475–82. PMID 17893649.

External links

• GeneReview/NIH/UW entry on Microphthalmia with Linear Skin Defects Syndrome