Monopolin
Protein complex
From Wikipedia, the free encyclopedia
Monopolin is a protein complex that in budding yeast is composed of the four proteins CSM1, HRR25, LRS4, and MAM1. Monopolin is required for the segregation of homologous centromeres to opposite poles of a dividing cell during anaphase I of meiosis.[1] This occurs by bridging DSN1 kinetochore proteins to sister kinetochores within the centromere to physically fuse them and allow for the microtubules to pull each homolog toward opposite mitotic spindles.[2]
| Monopolin complex subunit CSM1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | CSM1 | ||||||
| Entrez | 850447 | ||||||
| RefSeq (mRNA) | NM_001178792 | ||||||
| RefSeq (Prot) | NP_010009 | ||||||
| UniProt | P25651 | ||||||
| Other data | |||||||
| Chromosome | III: 0.26 - 0.26 Mb | ||||||
| |||||||
| Casein kinase I homolog HRR25 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| 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 | ||||||
| |||||||
| Monopolin complex subunit LRS4 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | LRS4 | ||||||
| Entrez | 852049 | ||||||
| RefSeq (mRNA) | NM_001180747 | ||||||
| RefSeq (Prot) | NP_010727 | ||||||
| UniProt | Q04087 | ||||||
| Other data | |||||||
| Chromosome | IV: 1.34 - 1.34 Mb | ||||||
| |||||||
| Monopolin complex subunit MAM1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | MAM1 | ||||||
| Entrez | 856843 | ||||||
| RefSeq (mRNA) | NM_001178997 | ||||||
| RefSeq (Prot) | NP_011032 | ||||||
| UniProt | P40065 | ||||||
| Other data | |||||||
| Chromosome | V: 0.37 - 0.37 Mb | ||||||
| |||||||
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, to bind to and fuse the sister kinetochores.[2] Microtubules can then attach to the kinetochores on the homologous centromeres and pull them toward opposite mitotic spindles to complete anaphase of meiosis I.
