Shugoshin 1 or Shugoshin-like 1, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

that in humans is encoded by the ''SGO1''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

Mechanisms

A physical mechanism that guarantees the accurate segregation of

sister chromatids A sister chromatid refers to the identical copies ( chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be 'one-half' of the du ...

during

mitosis Mitosis () is a part of the cell cycle in eukaryote, eukaryotic cells in which replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division by mitosis is an equational division which gives rise to genetically identic ...

arises from the ring shaped

cohesin Cohesin is a protein complex that mediates Establishment of sister chromatid cohesion, sister chromatid cohesion, homologous recombination, and Topologically associating domain, DNA looping. Cohesin is formed of SMC3, SMC1A, SMC1, RAD21, SCC1 an ...

complex consisting of 4 subunits ( SMC1A/ B, SMC3, SCC1, and SA1/ 2 in humans). This complex encircles the two sister chromatids and resists the pulling force of

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...

s. The characteristic X-shape chromosomes are formed due to the centromeric cohesin protected by Shugoshin- PP2A complex.

Kinetochore A kinetochore (, ) is a flared oblique-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers, which can be thought of as the ropes pulling chromosomes apart, attach during cell division to ...

localization of Sgo1-PP2A is dependent upon phosphorylation on histone H2A of

nucleosome A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone, histone proteins and resembles thread wrapped around a bobbin, spool. The nucleosome ...

, which is the important substrate of spindle checkpoint kinase

BUB1 Mitotic checkpoint serine/threonine-protein kinase BUB1 also known as BUB1 (budding uninhibited by benzimidazoles 1) is an enzyme that in humans is encoded by the ''BUB1'' gene. Bub1 is a serine/threonine protein kinase first identified in genet ...

. Centromeric cohesin and H2A-pT120 specify two distinct pools of Sgo1-PP2A at inner centromeres and kinetochores respectively, while the

CDK1 Cyclin-dependent kinase 1 also known as CDK1 or cell division cycle protein 2 homolog is a highly conserved protein that functions as a serine/threonine protein kinase, and is a key player in cell cycle regulation. It has been highly studied in ...

/cyclin B phosphorylation on Sgo1 is essential for Sgo1-PP2A to protect centromeric cohesin, not only for bringing PP2A to cohesin, but also physically shield out the negative regulator WAPAL from cohesin.

Mechanisms

References

Further reading