# Monopolin

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Protein complex

Monopolin complex subunit CSM1 Identifiers Organism S. cerevisiae Symbol CSM1 Entrez 850447 RefSeq (mRNA) NM_001178792 RefSeq (Prot) NP_010009 UniProt P25651 Other data Chromosome III: 0.26 - 0.26 Mb Search for Structures Swiss-model Domains InterPro

Casein kinase I homolog HRR25 Identifiers Organism S. cerevisiae Symbol HRR25 Entrez 855897 RefSeq (mRNA) NM_001184018 RefSeq (Prot) NP_015120 UniProt P29295 Other data EC number 2.7.11.1 Chromosome XVI: 0.16 - 0.17 Mb Search for Structures Swiss-model Domains InterPro

Monopolin complex subunit LRS4 Identifiers Organism S. cerevisiae Symbol LRS4 Entrez 852049 RefSeq (mRNA) NM_001180747 RefSeq (Prot) NP_010727 UniProt Q04087 Other data Chromosome IV: 1.34 - 1.34 Mb Search for Structures Swiss-model Domains InterPro

Monopolin complex subunit MAM1 Identifiers Organism S. cerevisiae Symbol MAM1 Entrez 856843 RefSeq (mRNA) NM_001178997 RefSeq (Prot) NP_011032 UniProt P40065 Other data Chromosome V: 0.37 - 0.37 Mb Search for Structures Swiss-model Domains InterPro

**Monopolin** is a [protein](/source/Protein) complex that in budding yeast is composed of the four proteins [CSM1](/source/CSM1), [HRR25](https://en.wikipedia.org/w/index.php?title=HRR25&action=edit&redlink=1), [LRS4](https://en.wikipedia.org/w/index.php?title=LRS4&action=edit&redlink=1), and [MAM1](https://en.wikipedia.org/w/index.php?title=MAM1&action=edit&redlink=1). Monopolin is required for the segregation of homologous [centromeres](/source/Centromere) to opposite poles of a dividing cell during [anaphase I of meiosis](/source/Meiosis).[1] This occurs by bridging [DSN1](/source/DSN1) kinetochore proteins to [sister kinetochores](/source/Kinetochores) within the centromere to physically fuse them and allow for the microtubules to pull each homolog toward opposite [mitotic spindles.](/source/Spindle_apparatus)[2]

## Molecular structure

Monopolin is composed of a 4 CSM1:2 LRS4 complex which forms a V-shaped structure with two globular heads at the ends, which are responsible for directly crosslinking sister kinetochores.[1] Bound to each CSM1 head is a MAM1 protein which recruits one copy of the HRR25 kinase.[3] The hydrophobic cavity on the CSM1 subunit allows the hydrophobic regions of Monopolin receptor and kinetochore protein, [DSN1](/source/DSN1), to bind to and fuse the sister kinetochores.[2] [Microtubules](/source/Microtubule) can then attach to the kinetochores on the homologous centromeres and pull them toward opposite mitotic spindles to complete anaphase of meiosis I.

## References

1. ^ [***a***](#cite_ref-pmid20723757_1-0) [***b***](#cite_ref-pmid20723757_1-1) Corbett KD, Yip CK, Ee LS, Walz T, Amon A, Harrison SC (August 2010). ["The monopolin complex crosslinks kinetochore components to regulate chromosome-microtubule attachments"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2955198). *Cell*. **142** (4): 556–67. [doi](/source/Doi_(identifier)):[10.1016/j.cell.2010.07.017](https://doi.org/10.1016%2Fj.cell.2010.07.017). [PMC](/source/PMC_(identifier)) [2955198](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2955198). [PMID](/source/PMID_(identifier)) [20723757](https://pubmed.ncbi.nlm.nih.gov/20723757).

1. ^ [***a***](#cite_ref-:0_2-0) [***b***](#cite_ref-:0_2-1) Plowman, Rebecca; Singh, Namit; Tromer, Eelco C.; Payan, Angel; Duro, Eris; Spanos, Christos; Rappsilber, Juri; Snel, Berend; Kops, Geert J. P.L.; Corbett, Kevin D.; Marston, Adele L. (2019-09-01). ["The molecular basis of monopolin recruitment to the kinetochore"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823300). *Chromosoma*. **128** (3): 331–354. [doi](/source/Doi_(identifier)):[10.1007/s00412-019-00700-0](https://doi.org/10.1007%2Fs00412-019-00700-0). [ISSN](/source/ISSN_(identifier)) [1432-0886](https://search.worldcat.org/issn/1432-0886). [PMC](/source/PMC_(identifier)) [6823300](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823300). [PMID](/source/PMID_(identifier)) [31037469](https://pubmed.ncbi.nlm.nih.gov/31037469).

1. **[^](#cite_ref-3)** Corbett, Kevin D.; Harrison, Stephen C. (2012-06-28). ["Molecular Architecture of the Yeast Monopolin Complex"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494995). *Cell Reports*. **1** (6): 583–589. [doi](/source/Doi_(identifier)):[10.1016/j.celrep.2012.05.012](https://doi.org/10.1016%2Fj.celrep.2012.05.012). [ISSN](/source/ISSN_(identifier)) [2211-1247](https://search.worldcat.org/issn/2211-1247). [PMC](/source/PMC_(identifier)) [3494995](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494995). [PMID](/source/PMID_(identifier)) [22813733](https://pubmed.ncbi.nlm.nih.gov/22813733).

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Adapted from the Wikipedia article [Monopolin](https://en.wikipedia.org/wiki/Monopolin) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Monopolin?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.