Cohesin subunit SA-2 (SA2) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''STAG2''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
SA2 is a subunit of the
Cohesin
Cohesin is a protein complex that mediates sister chromatid cohesion, homologous recombination, and DNA looping. Cohesin is formed of SMC3, SMC1, SCC1 and SCC3 ( SA1 or SA2 in humans). Cohesin holds sister chromatids together after DNA rep ...
complex which mediates
sister chromatid cohesion,
homologous recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may ...
and
DNA looping. In somatic cells cohesin is formed of
SMC3
Structural maintenance of chromosomes protein 3 (SMC3) is a protein that in humans is encoded by the SMC3 gene. SMC3 is a subunit of the Cohesin complex which mediates sister chromatid cohesion, homologous recombination and DNA looping. Cohesin ...
,
SMC1,
RAD21
Double-strand-break repair protein rad21 homolog is a protein that in humans is encoded by the ''RAD21'' gene. ''RAD21'' (also known as ''Mcd1'', ''Scc1'', ''KIAA0078'', ''NXP1'', ''HR21''), an essential gene, encodes a DNA double-strand break (D ...
and either
SA1 or SA2 whereas in
meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately resu ...
, cohesin is formed of SMC3,
SMC1B
Structural maintenance of chromosomes protein 1B (SMC-1B) is a protein that in humans is encoded by the ''SMC1B'' gene. SMC-1B belongs to a family of proteins required for chromatid cohesion and DNA recombination during meiosis and mitosis.
SMC1ß ...
,
REC8
Meiotic recombination protein REC8 homolog is a protein that in humans is encoded by the ''REC8'' gene.
Rec8 is a meiosis-specific component of the cohesin complex that binds sister chromatids in preparation for the two divisions of meiosis. Rec8 ...
and
SA3.
''STAG2'' is frequently mutated in a range of cancers and several other disorders.
Function
SA2 is part of the
cohesin complex, which is a structure that holds the sister
chromatids
A chromatid (Greek ''khrōmat-'' 'color' + ''-id'') is one half of a duplicated chromosome. Before replication, one chromosome is composed of one DNA molecule. In replication, the DNA molecule is copied, and the two molecules are known as chro ...
together after
DNA replication
In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...
. STAG2 has been shown to
interact
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...
with
STAG1
Cohesin subunit SA-1 (SA1) is a protein that in humans is encoded by the ''STAG1'' gene. SA1 is a subunit of the Cohesin complex which mediates sister chromatid cohesion, homologous recombination and DNA looping. In somatic cells cohesin is for ...
.
Role in Disease
Of the cohesin complex, STAG2 is the subunit where the most variants have been reported in cancer. This is thought to be because this gene is located in the X chromosome, therefore only one mutation is needed to inactivate it.
References
{{gene-X-stub