# Cystin-1

Cystin-1, also known as CYS1, is a novel cilia associated protein which in humans is encoded by the Cystin 1 gene on chromosome 2. The gene is highly expressed in the tissues of the kidneys. There are no known paralogs of Cystin-1 in humans, but has orthologs in mammals, birds, and some reptiles.

## Gene

The Cystin 1 gene is found on the negative strand of chromosome 2 in humans, with the exact location at 2p25.1. It contains 3 exons, spanning 3045 base pairs.

### Expression

The gene is overwhelmingly expressed within tissues in the kidneys. Lower expression levels are found in the ovaries, endometrium, lung, and gallbladder.

### Clinical Significance

Gene expression levels are increased in the ovary of those who experience ovarian endometriosis. There are also studies that connect the expression of Cystin to polycystic kidney disease, but direct impact is unknown.

## Protein

Cystin-1 consists of 158 amino acids and has a molecular weight of ~16.4kDa.

### Interactions

There are not many known interacting proteins with Cystin-1. Table 1 shows just a few possible interactions.
| Gene | Abbreviation | Functions |
| unc-119 lipid binding chaperone | UNC119 | Used to maintain localization |
| N-myritstoyltransferase 1 | NMT1 | Used to maintain localization |
| Phospholipase C gamme 1 | PLCG2 | Enable protein kinase activity |
| Regulator of Telomere elongation helicase 1 | RTEL1 | Enables ATP binding and DNA helicase activity |
| Epidermal growth factor receptor | EGFR | Biomarker for several diseases (including cancers) |
Table 1. Interactions with Cystin-1 based on affinity chromatography technology from Alliance of Genome Resources.

### Subcellular Location

Based on protein interactions with UNC119B, Cystin-1 is predicted to be localized within the cilia of the cell. How this protein makes its way to the cilia is still unknown.

## Homology
### Paralogs

There are currently no known paralog of Cystin-1 within humans.

### Orthologs

Orthologs of Cystin-1 were found in vertebrates, but not invertebrates.
| | Genus and Species | Common Name | Taxonomy | Date of divergence from Humans (MYA) | NCBI Accession | Sequence identity to humans | Sequence Similarity to humans |
| Mammal | Homo sapiens | Humans | Primates | 0 | NP_001032237 | 100% | 100% |
| | Pongo abelii | Sumatran Orangutan | Primates | 18 | XP_024098426 | 92.40% | 93.70% |
| | Monodon monoceros | Narwhal | Cetacea | 94 | XP_029088030.1 | 67.30% | 74.20% |
| | Phyllostomus hastatus | Spear nosed bat | Chiroptera | 94 | XP_045700664.1 | 66.50% | 72% |
| | Cervus canadensis | Elk | Artiodactyla | 94 | XP_043325302.1 | 65.40% | 71% |
| | Acinonyx jubatus | Cheetah | Carnivora | 94 | XP_026933675.0 | 61.90% | 68.50% |
| | Mus musculus | House Mouse | Rodentia | 87 | AAI39303.0 | 58.20% | 65.80% |
| | Manis javanica | Sunda Pangolin | Pholidota | 94 | KAI5938697.0 | 27.10% | 29% |
| Reptilia | | | | | | | |
| | Gopherus evgoodei | Goode's Thornscrub Tortiose | Testudines | 319 | XP_030411302.1 | 38% | 44.30% |
| | Varanus komodoensis | Komodo Dragon | Squamata | 319 | XP_044275134.1 | 36.30% | 44% |
| | Lacerta agilis | Sand Lizard | Squamata | 319 | XP_032998985.1 | 35.60% | 44.40% |
| | Chelydra serpentina | Common Snapping Turtle | Testudines | 318 | KAG6933055 | 23% | 26.60% |
| Aves | | | | | | | |
| | Vidua chalybeata | Village Indigo Brid | Passeriformes | 319 | XP_053794446.1 | 36% | 40.90% |
| | Poecile atricapillus | Black Capped Chickadee | Passeriformes | 319 | XP_058691046.1 | 35.70% | 41.50% |
| | Pipra filicauda | Wire-tailed Manakin | Passeriformes | 319 | XP_039240811.1 | 35.60% | 39.50% |
| | Apus apus | Common Swift | Apodiformes | 319 | XP_051469776.1 | 35.40% | 42.30% |
Table 2. Species that have the Cystin-1 ortholog