| CHLSN | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Identifiers | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | CHLSN, YCR016W, chromosome 7 open reading frame 50, C7orf50, Cholesin, Uncharacterized Protein C7orf50 | |||||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | MGI: 1920462; GeneCards: CHLSN | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Wikidata | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Cholesin is a protein which in humans is encoded by the gene CHLSN. It functions as a hormone that regulates the synthesis of cholesterol, and the way it does it is distinctive in that it can be involved in either increasing or decreasing synthesis, rather than a simple one-way effect. This function appears to be occur through binding to its receptor GPR146.
It is most highly produced in the upper digestive system and respiratory system, in addition to the (hormone producing) endocrine system. Additionally, this gene is predicted to be a microRNA (miRNA) protein coding host gene, meaning that it may contain miRNA genes in its introns and/or exons.
CHLSN is located on the short arm of chromosome 7 (7p22.3), and spans 160,361 bps on the minus (-) strand and contains a total of 13 exons.
Genes within the neighborhood of CHLSN are the following: LOC105375120, GPR146, LOC114004405, LOC107986755, ZFAND2A, LOC102723758, LOC106799841, COX19, ADAP1, CYP2W1, MIR339, GPER1, and LOC101927021.
Cholesin is conserved in chimpanzees, Rhesus monkeys, dogs, cows, mice, rats, and chickens, along with 307 other organisms from mammals to fungi.
CHLSN has a total of 7 experimentally curated mRNA transcripts. The longest and most complete of these transcripts (transcript 4) being 2138bp, producing a 194 amino acid-long (aa) protein, and consisting of 5 exons. Of these transcripts, four of them encode for the same 194aa protein (isoform a), only differing in their 5' and 3' untranslated regions (UTRs). The three other transcripts encode isoform b, c, and d, respectively. The table below is representative of these transcripts.
| CHLSN Experimentally Determined
NCBI Reference Sequences (RefSeq) mRNA Transcripts | |||||
| Name | NCBI Accession # | Transcript Length | # of Exons | Protein Length | Isoform |
|---|---|---|---|---|---|
| Transcript Variant 1 | NM_032350.5 | 1311bp | 5 | 194aa | a |
| Transcript Variant 2 | NM_001134395.1 | 1301bp | 5 | 194aa | a |
| Transcript Variant 3 | NM_001134396.1 | 1282bp | 5 | 194aa | a |
| Transcript Variant 4 | NM_001318252.2 | 2138bp | 5 | 194aa | a |
| Transcript Variant 7 | NM_001350968.1 | 1081bp | 6 | 193aa | b |
| Transcript Variant 8 | NM_001350969.1 | 1500bp | 5 | 180aa | c |
| Transcript Variant 9 | NM_001350970.1 | 1448bp | 3 | 60aa | d |
Alternatively, when the primary genomic assembly, GRCh38.p13, is used for annotation (NCBI: NC_000007.14), there are 10 computationally predicted mRNA transcripts. The most complete and supported of these transcripts (transcript variant X6) is 1896bp, producing a 225aa-long protein. In total, there are 6 different isoforms predicted for CHLSN. Of these transcripts, 5 of them encode for the same isoform (X3). The remaining transcripts encode isoforms X2, X4, X5, X6, and X7 as represented below.
| CHLSN Computationally Determined
NCBI Reference Sequences (RefSeq) mRNA Transcripts | ||||
| Name | NCBI Accession # | Transcript Length | Protein Length | Isoform |
|---|---|---|---|---|
| Transcript Variant X2 | XM_017012719.1 | 1447bp | 375aa | X2 |
| Transcript Variant X3 | XM_011515582.3 | 1192bp | 225aa | X3 |
| Transcript Variant X4 | XM_024446977.1 | 1057bp | 193aa | X4 |
| Transcript Variant X5 | XM_011515581.3 | 1240bp | 225aa | X3 |
| Transcript Variant X6 | XM_011515584.2 | 1896bp | 225aa | X3 |
| Transcript Variant X7 | XM_017012720.2 | 1199bp | 225aa | X3 |
| Transcript Variant X8 | XM_011515583.2 | 1215bp | 225aa | X3 |
| Transcript Variant X9 | XM_017012721.2 | 2121bp | 211aa | X5 |
| Transcript Variant X10 | XM_024446978.1 | 2207bp | 180aa | X6 |
| Transcript Variant X11 | XM_024446979.1 | 933bp | 93aa | X7 |
Based on the experimentally determined CHLSN mRNA transcript variant 4, the 5' UTR of CHLSN is 934 nucleotides (nt) long, while the 3' UTR is 619nt. The coding sequence (CDS) of this transcript spans nt 935..1519 for a total length of 584nt and is encoded in reading frame 2.
The CHLSN Isoform a's 194aa protein sequence from NCBI is as follows:
>NP_001127867.1 cholesin isoform a [Homo sapiens] MAKQKRKVPEVTEKKNKKLKKASAEGPLLGPEAAPSGEGAGSKGEAVLRPGLDAEPELSPEEQRVLERKL 70 KKERKKEERQRLREAGLVAQHPPARRSGAELALDYLCRWAQKHKNWRFQKTRQTWLLLHMYDSDKVPDEH 140 FSTLLAYLEGLQGRARELTVQKAEALMRELDEEGSDPPLPGRAQRIRQVLQLLS 194
The underlined region within the sequence is indicative of a domain known as DUF2373 ("domain of unknown function 2373"), found in isoforms a, b, and c.
Cholesin has a predicted molecular weight (Mw) of 22 kDa, making cholesin smaller than the average protein (52 kDa). The isoelectric point (theoretical pI) for this isoform is 9.7, meaning that cholesin is slightly basic. As for charge runs and patterns within isoform a, there is a significant mixed charge (*) run (-++0++-+++--+) from aa67 to aa79 and an acidic (-) run from aa171 – aa173. It is likely that this mixed charge run encodes the protein-protein interaction (PPI) site of cholesin.
Characterization of the protein has shown binding to GPR146. Based on a proposed role in regulation of serum cholesterol levels in response to dietary cholesterol intake, the protein has been called cholesin.
DUF2373 is a domain of unknown function found in the cholesin. This is a highly conserved c-terminal region found from fungi to humans. As for motifs, a bipartite nuclear localization signal (NLS) was predicted from aa6 to aa21, meaning that cholesin is likely localized in the nucleus. Interestingly, a nuclear export signal (NES) is also found within cholesin at the following amino acids: 150, and 153 - 155, suggesting that cholesin has function both inside and outside the nucleus.

The majority of cholesin (isoform a) secondary structure is made up of alpha helices, with the remainder being small portions of random coils, beta turns, or extended strands.
The tertiary structure of cholesin consists primarily of alpha helices as determined I-TASSER.
The interaction network (quaternary structure) involving the cholesin has significantly more (p < 1.0e-16) interactions than a randomly selected set of proteins.
| Biological Processes | rRNA processing | maturation of 5.8S, LSU, and SSU rRNA |
| Molecular Functions | catalytic activity, acting on RNA | ATP-dependent RNA helicase activity |
| Cellular Components | nucleolus | preribosomes |
| Reactome Pathways | major pathway of rRNA processing in the nucleolus and cytosol | rRNA modification in the nucleus and cytosol |
| Protein Domains and Motifs | helicase conserved C-terminal domain | DEAD/DEAH box helicase |
The closest predicted functional partners of cholesin are the following proteins: DDX24, DDX52, PES1, EBNA1BP2, RSLD1, NOP14, FTSJ3, KRR1, LYAR, and PWP1. These proteins are predicted to co-express rather than bind directly to cholesin and each other.

CHLSN has 6 predicted promoter regions. The promoter with the greatest number of transcripts and CAGE tags overall is promoter set 6 (GXP_6755694) on ElDorado by Genomatix. This promoter region is on the minus (-) strand and has a start position of 1,137,965 and an end position of 1,139,325, making this promoter 1,361bp long. It has 16 coding transcripts and the transcript with the greatest identity to C7orf50 transcript 4 is transcript GXT_27788039 with 98746 CAGE tags.
| Promoter ID | Start Position | End Position | Length | # of Coding Transcripts | Greatest # of CAGE Tags in Transcripts |
|---|---|---|---|---|---|
| GXP_9000582 | 1013063 | 1013163 | 1101bp | 0 | N/A |
| GXP_6755691 | 1028239 | 1030070 | 1832bp | 4 | 169233 |
| GXP_6053282 | 1055206 | 1056306 | 1101bp | 1 | 449 |
| GXP_3207505 | 1127288 | 1128388 | 1101bp | 1 | 545 |
| GXP_9000584 | 1130541 | 1131641 | 1101bp | 0 | N/A |
| GXP_6755694 | 1137965 | 1139325 | 1361bp | 16 | 100,070 |
The CpG island associated with this promoter has 75 CpGs (22% of island), and is 676bp long. The C count plus G count is 471, the percentage C or G is 70% within this island, and the ratio of observed to expected CpG is 0.91.

As determined by MatInspector at Genomatix, the following transcription factor (TFs) families are most highly predicted to bind to CHLSN in the promoter region.
| Transcription Factor | Detailed Family Information |
|---|---|
| NR2F | Nuclear receptor subfamily 2 factors |
| PERO | Peroxisome proliferator-activated receptor |
| HOMF | Homeodomain transcription factors |
| PRDM | PR (PRDI-BF1-RIZ1 homologous) domain transcription factor |
| VTBP | Vertebrate TATA binding protein factor |
| HZIP | Homeodomain-leucine zipper transcription factors |
| ZTRE | Zinc transcriptional regulatory element |
| XBBF | X-box binding factors |
| SP1F | GC-Box factors SP1/GC |
| CAAT | CCAAT binding factors |
| ZF57 | KRAB domain zinc finger protein 57 |
| CTCF | CTCF and BORIS gene family, transcriptional regulators with highly conserved zinc finger domains |
| MYOD | Myoblast determining factors |
| KLFS | Krueppel like transcription factors |
CHLSN shows ubiquitous expression in the kidneys, brain, fat, prostate, spleen and 22 other tissues and low tissue and immune cell specificity . This expression is very high, 4 times above the average gene; therefore, there is a higher abundance of CHLSN mRNA than the average gene within a cell. There does not appear to be a definitive cell type in which this gene is not expressed.
The mRNA of CHLSN is predicted to have exonic splicing enhancers, in which SR proteins can bind, at bp positions 45 (SRSF1 (IgM-BRCA1)), 246 (SRSF6), 703 (SRSF5), 1301 (SRSF1), and 1308 (SRSF2)
There are many poorly conserved miRNA binding sites predicted within the 3'UTR of CHLSN mRNA. The notable miRNA families that are predicted to bind to CHLSN mRNA and regulate/repress transcription are the following: miR-138-5p, miR-18-5p, miR-129-3p, miR-124-3p.1, miR-10-5p, and miR-338-3p.
Cholesin is predicted to localize intercellularly in both the nucleus and cytoplasm, but primarily within the nucleoplasm and nucleoli.
Cholesin is predicted to be mucin-type GalNAc o-glycosylated at the following amino acid sites: 12, 23, 36, 42, 59, and 97. Additionally, this protein is predicted to be SUMOylated at aa71 with the SUMO protein binding from aa189 through aa193. Cholesin is also predicted to be kinase-specific phosphorylated at the following amino acids: 12, 23, 36, 42, 59, 97, 124, 133, 159, and 175. Interestingly, many of these sites overlap with the o-glycosylation sites. Of these phosphorylation sites, the majority are serines (53%) with the remainder being either tyrosines or threonines. The most associated kinases with these sites are the following kinase groups: AGC, CAMK, TKL, and STE. Finally, this protein is predicted to have 8 glycations of the ε amino groups of lysines at the following sites: aa3, 5, 14, 15, 17, 21, 76, and 120.
No paralogs of cholesin have been detected in the human genome; however, there is slight evidence (58% similarity) of a paralogous DUF2373 domain in the protein of KIDINS220.
Below is a table of a variety of orthologs of the human CHLSN. The table includes closely, moderately, and distantly related orthologs. CHLSN is highly evolutionary conserved from mammals to fungi. When these ortholog sequences are compared, the most conserved portions are those of DUF2373. CHLSN has evolved moderately and evenly over time with a divergence rate greater than Hemoglobin but less than Cytochrome C.
| Genus and species | Common name | Taxon Class | Date of Divergence (MYA) | Accession # | Length (AA) | % identity w/ human |
|---|---|---|---|---|---|---|
| Homo sapiens | Human | Mammalia | N/A | NM_001318252.2 | 194aa | 100% |
| Tupaia chinensis | Chinese Tree Shrew | Mammalia | 82 | XP_006167949.1 | 194aa | 76% |
| Dasypus novemcinctus | Nine-banded Armadillo | Mammalia | 105 | XP_004483895.1 | 198aa | 70% |
| Miniopterus natalens | Natal Long-fingered Bat | Mammalia | 96 | XP_016068464.1 | 199aa | 69% |
| Protobothrops mucrosquamatus | Brown-spotted Pit Viper | Reptilia | 312 | XP_015673296.1 | 196aa | 64% |
| Balearica regulorum gibbericeps | Grey-crowned Crane | Aves | 312 | XP_010302837.1 | 194aa | 61% |
| Falco peregrinus | Peregrine Falcon | Aves | 312 | XP_027635198.1 | 193aa | 59% |
| Xenopus laevis | African Clawed Frog | Amphibia | 352 | XP_018094637.1 | 198aa | 50% |
| Electrophorus electricus | Electric Eel | Actinopterygii | 435 | XP_026880604.1 | 195aa | 53% |
| Rhincodon typus | Whale Shark | Chondrichthyes | 465 | XP_020372968.1 | 195aa | 52% |
| Ciona intestinalis | Sea Vase | Ascidiacea | 676 | XP_026696561.1 | 282aa | 37% |
| Octopus bimaculoides | California Two-spot Octopus | Cephalopoda | 797 | XP_014772175.1 | 221aa | 40% |
| Priapulus caudatus | Priapulus | Priapulida | 797 | XP_014663190.1 | 333aa | 39% |
| Bombus terrestris | Buff-tailed Bumblebee | Insecta | 797 | XP_012171653.1 | 260aa | 32% |
| Actinia tenebrosa | Australian Red Waratah Sea Anemone | Anthozoa | 824 | XP_031575029.1 | 330aa | 43% |
| Trichoplax adhaerens | Trichoplax | Trichoplacidae | 948 | XP_002110193.1 | 137aa | 44% |
| Spizellomyces punctatus | Branching Chytrid Fungi | Fungi | 1105 | XP_016610491.1 | 412aa | 29% |
| Eremothecium cymbalariae | Fungi | Fungi | 1105 | XP_003644395.1 | 266aa | 25% |
| Quercus suber | Cork Oak Tree | Plantae | 1496 | XP_023896156.1 | 508aa | 30% |
| Plasmopara halstedii | Downy Mildew of Sunflower | Oomycetes | 1768 | XP_024580369.1 | 179aa | 26% |

| Name of Protein | Name of Gene | Function | UniProt Accession # |
|---|---|---|---|
| THAP1 domain-containing protein 1 | THAP1 | DNA-binding transcription regulator that regulates endothelial cell proliferation and G1/S cell-cycle progression. | Q9NVV9 |
| Protein Tax-2 | tax | Transcriptional activator that activates both the viral long terminal repeat (LTR) and cellular promoters via activation of CREB, NF-kappa-B, SRF and AP-1 pathways. | P03410 |
| Major Prion Protein | PRNP | Its primary physiological function is unclear. May play a role in neuronal development and synaptic plasticity. May be required for neuronal myelin sheath maintenance. May promote myelin homeostasis through acting as an agonist for ADGRG6 receptor. May play a role in iron uptake and iron homeostasis. | P04156 |
| Aldehyde dehydrogenase X, mitochondrial | ALDH1B1 | Pay a major role in the detoxification of alcohol-derived acetaldehyde. They are involved in the metabolism of corticosteroids, biogenic amines, neurotransmitters, and lipid peroxidation. | P30837 |
| Cell growth-regulating nucleolar protein | LYAR | Plays a role in the maintenance of the appropriate processing of 47S/45S pre-rRNA to 32S/30S pre-rRNAs and their subsequent processing to produce 18S and 28S rRNAs. | Q9NX58 |
| Coiled-coil domain-containing protein 85B | CCDC85B | Functions as a transcriptional repressor. | Q15834 |
| Nucleolar protein 56 | NOP56 | Involved in the early to middle stages of 60S ribosomal subunit biogenesis. Core component of box C/D small nucleolar ribonucleoprotein (snoRNP) particles. Required for the biogenesis of box C/D snoRNAs such U3, U8 and U14 snoRNAs. | O00567 |
| rRNA 2'-O-methyltransferase fibrillarin | FBL | Has the ability to methylate both RNAs and proteins. Involved in pre-rRNA processing by catalyzing the site-specific 2'-hydroxyl methylation of ribose moieties in pre-ribosomal RNA. | P22087 |
| 40S ribosomal protein S6 | RPS6 | May play an important role in controlling cell growth and proliferation through the selective translation of particular classes of mRNA. | P62753 |
CHLSN has been noted in a variety of genome-wide association studies (GWAS) and has been shown to be associated with type 2 diabetes among sub-Saharan Africans, daytime sleepiness in African-Americans, prenatal exposure to particulate matter, heritable DNA methylation marks associated with breast cancer, DNA methylation in relation to plasma carotenoids and lipid profile, and has significant interactions with prion proteins.
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