STAG2

The protein encoded by this gene is a subunit of the cohesin complex, which regulates the separation of sister chromatids during cell division. Targeted inactivation of this gene results in chromatid cohesion defects and aneuploidy, suggesting that genetic disruption of cohesin is a cause of aneuploidy in human cancer. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.

Full Name

stromal antigen 2

Function

Component of cohesin complex, a complex required for the cohesion of sister chromatids after DNA replication. The cohesin complex apparently forms a large proteinaceous ring within which sister chromatids can be trapped. At anaphase, the complex is cleaved and dissociates from chromatin, allowing sister chromatids to segregate. The cohesin complex may also play a role in spindle pole assembly during mitosis.

Biological Process

Biological Process cell divisionIEA:UniProtKB-KW
Biological Process establishment of meiotic sister chromatid cohesion1 PublicationIC:ComplexPortal
Biological Process mitotic spindle assemblyManual Assertion Based On ExperimentIMP:UniProtKB
Biological Process sister chromatid cohesionManual Assertion Based On ExperimentIMP:UniProtKB

Cellular Location

Nucleus
Chromosome
Chromosome, centromere
Associates with chromatin. Before prophase it is scattered along chromosome arms. During prophase, most of cohesin complexes dissociate from chromatin probably because of phosphorylation by PLK1, except at centromeres, where cohesin complexes remain. At anaphase, the RAD21 subunit of cohesin is cleaved, leading to the dissociation of the complex from chromosomes, allowing chromosome separation. In germ cells, cohesin complex dissociates from chromatin at prophase I, and may be replaced by a meiosis-specific cohesin complex.

Involvement in disease

Mullegama-Klein-Martinez syndrome (MKMS):
An X-linked neurodevelopmental disorder with variable features including intellectual deficiency, microcephaly, microtia, hearing loss, developmental delay, dysmorphic features, language delay, congenital heart defect, and clinodactyly of the 5th finger.
Holoprosencephaly 13, X-linked (HPE13):
An X-linked form of holoprosencephaly, a structural anomaly of the brain in which the developing forebrain fails to correctly separate into right and left hemispheres. Holoprosencephaly is genetically heterogeneous and associated with several distinct facies and phenotypic variability. HPE13 features range from full alobar holoprosencephaly with cyclopia to semilobar holoprosencephaly or septooptic dysplasia. Dysmorphic features include microcephaly, hypotelorism, low-set ears, micrognathia, and cleft lip/palate. Patients with a more severe phenotype may die in the newborn period, whereas those with a less severe phenotype show global developmental delay.

PTM

Phosphorylated by PLK1. The large dissociation of cohesin from chromosome arms during prophase is partly due to its phosphorylation (By similarity).