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CYCS cytochrome c, somatic [ Homo sapiens (human) ]

Gene ID: 54205, updated on 6-Sep-2022


Official Symbol
CYCSprovided by HGNC
Official Full Name
cytochrome c, somaticprovided by HGNC
Primary source
See related
Ensembl:ENSG00000172115 MIM:123970; AllianceGenome:HGNC:19986
Gene type
protein coding
RefSeq status
Homo sapiens
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo
Also known as
This gene encodes a small heme protein that functions as a central component of the electron transport chain in mitochondria. The encoded protein associates with the inner membrane of the mitochondrion where it accepts electrons from cytochrome b and transfers them to the cytochrome oxidase complex. This protein is also involved in initiation of apoptosis. Mutations in this gene are associated with autosomal dominant nonsyndromic thrombocytopenia. Numerous processed pseudogenes of this gene are found throughout the human genome.[provided by RefSeq, Jul 2010]
Broad expression in heart (RPKM 66.9), colon (RPKM 54.4) and 24 other tissues See more
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Genomic context

See CYCS in Genome Data Viewer
Exon count:
Annotation release Status Assembly Chr Location
110 current GRCh38.p14 (GCF_000001405.40) 7 NC_000007.14 (25118656..25125260, complement)
110 current T2T-CHM13v2.0 (GCF_009914755.1) 7 NC_060931.1 (25253926..25260530, complement)
105.20220307 previous assembly GRCh37.p13 (GCF_000001405.25) 7 NC_000007.13 (25158275..25164879, complement)

Chromosome 7 - NC_000007.14Genomic Context describing neighboring genes Neighboring gene gasdermin E Neighboring gene translation initiation factor IF-2-like Neighboring gene Sharpr-MPRA regulatory region 12520 Neighboring gene oxysterol binding protein like 3 Neighboring gene small nuclear ribonucleoprotein polypeptide C pseudogene 19 Neighboring gene uncharacterized LOC124901603 Neighboring gene chromosome 7 open reading frame 31 Neighboring gene uncharacterized LOC124901602 Neighboring gene uncharacterized LOC105375191

Genomic regions, transcripts, and products


  • Project title: HPA RNA-seq normal tissues
  • Description: RNA-seq was performed of tissue samples from 95 human individuals representing 27 different tissues in order to determine tissue-specificity of all protein-coding genes
  • BioProject: PRJEB4337
  • Publication: PMID 24309898
  • Analysis date: Wed Apr 4 07:08:55 2018


GeneRIFs: Gene References Into Functions

What's a GeneRIF?


Associated conditions

Description Tests
Thrombocytopenia 4
MedGen: C2677608 OMIM: 612004 GeneReviews: Not available
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EBI GWAS Catalog

Genome-wide association study of the rate of cognitive decline in Alzheimer's disease.
EBI GWAS Catalog

HIV-1 interactions

Replication interactions

Interaction Pubs
Knockdown of cytochrome c, somatic (CYCS) by siRNA inhibits HIV-1 replication in HeLa P4/R5 cells PubMed

Protein interactions

Protein Gene Interaction Pubs
Envelope surface glycoprotein gp120 env PDGF protects neurons from gp120-induced cytotoxicity through an increased phosphorylation of both GSK-3beta and Bad, the downregulation of the proapoptotic protein Bax, and inhibition of gp120-induced release of mitochondrial cytochrome C PubMed
env Apoptosis induced by HIV-1 gp120/gp41 is involved in the translocation of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria to an extra-mitochondrial localization and in the dissipation of the mitochondrial transmembrane potential PubMed
env Treatment of cerebrocortical cultures with HIV-1 gp120 results in increased caspase-3 proteolytic activity, mitochondrial release of cytochrome c, and neuronal apoptosis PubMed
Envelope surface glycoprotein gp160, precursor env Treatment of CD4+ cells with HIV-1 gp160 causes intracellular calcium increase followed by the release of cytochrome c from mitochondria; association of BAD with Bcl-xL is observed, and a portion of BAD is dephosphorylated after gp160 induction PubMed
Nef nef eEF1A/Nef complexes contain tRNAs and block stress-induced apoptosis in monocyte-derived macrophages through tRNA binding to cytochrome c PubMed
Tat tat HIV-1 Tat induces apoptosis of human blood-retinal barrier-associated cells by downregulation of BCL2 and upregulation of BAK, BAX, and cytochrome c in a dose-dependent manner PubMed
tat HIV-1 Tat-induced PARP cleavage during mitotic arrest occurs downstream of Tat-induced cytochrome c release during mitotic arrest in CD4+ T-lymphocytes PubMed
tat FasL-induced release of cytochrome c and activation of caspase-9 are inhibited in HIV-1 Tat101-expressing Jurkat cells due to high stability of the mitochondrial inner membrane electrochemical potential PubMed
tat Both HIV-1 Tat 47-59 and FITC-labeled Tat 47-59 peptides upregulate gene expression of cytochrome c, somatic (CYCS) in U-937 macrophages PubMed
tat HIV-1 Tat (specifically, amino acids 38-72), enhances tubulin polymerization and triggers the mitochondrial pathway to induce T cell apoptosis as shown in vitro by the release of cytochrome c from isolated mitochondria PubMed
Vpr vpr HIV-1 Vpr induces downregulation of the Bcl-xl protein, upregulation of the Bax expression, and the cytochrome c release from the mitochondria in multidrug-resistant human colorectal cancer cells PubMed
vpr Overproduction of EEF2 blocks HIV-1 Vpr-induced cell death both in fission yeast and human cells, suppresses caspase 9 and caspase 3-mediated apoptosis induced by Vpr, and reduces cytochrome c release induced by Vpr PubMed
retropepsin gag-pol HIV-1 PR interacts with mitochondrial proteins VDAC, cytochrome c, TOM22, and Bax in HeLa cells PubMed
gag-pol HIV-1 protease directly cleaves and activates procaspase 8 in T cells, which is associated with cleavage of BID, mitochondrial release of cytochrome c, activation of the downstream caspases 9 and 3, and cleavage of DFF and PARP PubMed

Go to the HIV-1, Human Interaction Database

Pathways from PubChem


Products Interactant Other Gene Complex Source Pubs Description

General gene information



Gene Ontology Provided by GOA

Function Evidence Code Pubs
enables electron transfer activity IEA
Inferred from Electronic Annotation
more info
enables heme binding TAS
Traceable Author Statement
more info
enables metal ion binding IEA
Inferred from Electronic Annotation
more info
enables protein binding IPI
Inferred from Physical Interaction
more info
Component Evidence Code Pubs
part_of apoptosome IPI
Inferred from Physical Interaction
more info
located_in cytosol IDA
Inferred from Direct Assay
more info
located_in cytosol IMP
Inferred from Mutant Phenotype
more info
located_in cytosol TAS
Traceable Author Statement
more info
located_in mitochondrial inner membrane TAS
Traceable Author Statement
more info
is_active_in mitochondrial intermembrane space IBA
Inferred from Biological aspect of Ancestor
more info
located_in mitochondrial intermembrane space IDA
Inferred from Direct Assay
more info
located_in mitochondrial intermembrane space TAS
Traceable Author Statement
more info
located_in mitochondrion HDA PubMed 
located_in mitochondrion IDA
Inferred from Direct Assay
more info
located_in nucleus HDA PubMed 
located_in nucleus IDA
Inferred from Direct Assay
more info
located_in respirasome IEA
Inferred from Electronic Annotation
more info

NCBI Reference Sequences (RefSeq)

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RefSeqs maintained independently of Annotated Genomes

These reference sequences exist independently of genome builds. Explain

These reference sequences are curated independently of the genome annotation cycle, so their versions may not match the RefSeq versions in the current genome build. Identify version mismatches by comparing the version of the RefSeq in this section to the one reported in Genomic regions, transcripts, and products above.


  1. NG_023438.1 RefSeqGene

    GenBank, FASTA, Sequence Viewer (Graphics), LRG_876

mRNA and Protein(s)

  1. NM_018947.6NP_061820.1  cytochrome c

    See identical proteins and their annotated locations for NP_061820.1

    Status: REVIEWED

    Source sequence(s)
    AC007487, AI365318, BC024216, DB447825
    Consensus CDS
    P99999, Q96BV4
    ENSP00000307786.2, ENST00000305786.7
    Conserved Domains (1) summary
    Cyc7; Cytochrome c2 [Energy production and conversion]

RefSeqs of Annotated Genomes: Homo sapiens Annotation Release 110 details...Open this link in a new tab

The following sections contain reference sequences that belong to a specific genome build. Explain

Reference GRCh38.p14 Primary Assembly


  1. NC_000007.14 Reference GRCh38.p14 Primary Assembly

    25118656..25125260 complement
    GenBank, FASTA, Sequence Viewer (Graphics)

Alternate T2T-CHM13v2.0


  1. NC_060931.1 Alternate T2T-CHM13v2.0

    25253926..25260530 complement
    GenBank, FASTA, Sequence Viewer (Graphics)