Shugoshin-like 1 (hSgo1, serologically defined breast cancer antigen NY-BR-85, SGOL1, SGO1)
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Function
- role in chromosome cohesion during mitosis by preventing premature dissociation of cohesin complex from centromeres after prophase, when most of cohesin complex dissociates from chromosomes arms
- may act by preventing phosphorylation of the STAG2 subunit of cohesin complex at the centromere, ensuring cohesin persistence at centromere until cohesin cleavage by ESPL1/separase at anaphase
- ubiquitinated by the anaphase promoting complex (APC) at the onset of anaphase, resulting in its degradation
Structure
- belongs to the shugoshin family
- D-box (destruction box) mediates interaction with APC proteins, & may act as a recognition signal for degradation via the ubiquitin-proteasome pathway
Compartment
- nucleus, centromere
- localizes to the centromere
- BUB1 is required for centromeric localization
- during prometaphase, it localizes to a single focus, while at metaphase, it localizes to 2 spots corresponding to the 2 centromeres
Alternative splicing
named isoforms=7
Expression
- widely expressed
- highly expressed in testis
- expressed in lung, small intestine, breast, liver & placenta
- appears in prophase cells & remains present until metaphase
- strongly decreases at the onset of anaphase & completely disapears at telophase
- not present in interphase cells (at protein level)
Pathology
- strongly overexpressed in 90% of breast cancers tested