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External IDs OMIM603871 MGI1858419 HomoloGene2991 GeneCards: BYSL Gene
RNA expression pattern
PBB GE BYSL 203612 at tn.png
More reference expression data
Species Human Mouse
Entrez 705 53414
Ensembl ENSG00000112578 ENSMUSG00000023988
UniProt Q13895 O54825
RefSeq (mRNA) NM_004053 NM_016859
RefSeq (protein) NP_004044 NP_058555
Location (UCSC) Chr 6:
41.89 – 41.9 Mb
Chr 17:
47.6 – 47.61 Mb
PubMed search [1] [2]

Bystin is a protein that in humans is encoded by the BYSL gene.[1][2][3]


Bystin is expressed as a 2-kb major transcript and a 3.6-kb minor transcript in SNG-M cells and in human trophoblastic teratocarcinoma HT-H cells. Protein binding assays determined that bystin binds directly to trophinin and tastin, and that binding is enhanced when cytokeratins 8 and 18 are present. Immunocytochemistry of HT-H cells showed that bystin colocalizes with trophinin, tastin, and the cytokeratins, suggesting that these molecules form a complex in trophectoderm cells at the time of implantation. Using immunohistochemistry it was determined that trophinin and bystin are found in the placenta from the sixth week of pregnancy. Both proteins were localized in the cytoplasm of the syncytiotrophoblast in the chorionic villi and in endometrial decidual cells at the uteroplacental interface. After week 10, the levels of trophinin, tastin, and bystin decreased and then disappeared from placental villi.[3]


BYSL has been shown to interact with TROAP.[4]


  1. ^ Pack SD, Pak E, Tanigami A, Ledbetter DH, Fukuda MN (Mar 1999). "Assignment1 of the bystin gene BYSL to human chromosome band 6p21.1 by in situ hybridization". Cytogenet Cell Genet 83 (1–2): 76–7. doi:10.1159/000015131. PMID 9925933. 
  2. ^ Miyoshi M, Okajima T, Matsuda T, Fukuda MN, Nadano D (May 2007). "Bystin in human cancer cells: intracellular localization and function in ribosome biogenesis". Biochem J 404 (3): 373–81. doi:10.1042/BJ20061597. PMC 1896285. PMID 17381424. 
  3. ^ a b "Entrez Gene: BYSL bystin-like". 
  4. ^ Suzuki N, Zara J, Sato T, Ong E, Bakhiet N, Oshima RG et al. (Apr 1998). "A cytoplasmic protein, bystin, interacts with trophinin, tastin, and cytokeratin and may be involved in trophinin-mediated cell adhesion between trophoblast and endometrial epithelial cells". Proc. Natl. Acad. Sci. U.S.A. 95 (9): 5027–32. doi:10.1073/pnas.95.9.5027. PMC 20207. PMID 9560222. 

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