SMC1A Gene

SMC1A is the acronym for "Structural Maintenance Of Chromosomes 1A". The SMC1a gene is a protein coding gene located on chromosome Xp11.22. The encoded protein is involved in chromosome cohesion during the cell cycle and in DNA repair. It forms the central component of the cohesin complex. The SMC1A gene belongs to the SMC gene family and is located in a region of the X chromosome that escapes X inactivation. Mutations in this gene lead to Cornelia de Lange syndrome. Alternative splicing results in multiple transcript variants encoding different isoforms.

The correct cohesion of sister chromatids is a prerequisite for the correct segregation of chromosomes during cell division. The cohesin-protein complex is required for sister chromatid cohesion. The complex consists in part of two structural maintenance of chromosomes (SMC) proteins, SMC3 + either SMC1B or SMCA1. Most cohesin complexes detach from chromosomes before mitosis. The complexes at the kinetochore, however, persist. The protein encoded by SMC1A interacts with BRCA1 and probably plays a role in DNA repair....

The cohesin complex is required for the cohesion of sister chromatids after DNA replication. The cohesin complex apparently forms a large protein ring in which sister chromatids can be held together. In anaphase, the complex is cleaved and detaches from chromatin, allowing sister chromatids to separate. The cohesin complex may also play a role in the assembly of spindle poles during mitosis. Furthermore, it is involved in DNA repair via its interaction with BRCA1 and its associated phosphorylation by ATM or via its phosphorylation by ATR.

1. K. Nasmyth et al. (2005) The structure and function of SMC and kleisin complexes. Annual Review of Biochemistry 74, 595-648
2. Haering CH et al (2008) The cohesin ring concatenates sister DNA molecules. Nature 454: 297-301.
3. McNairn AJ et al. (2008) Cohesinopathies: one ring, many obligations. Mutation Research 647: 103-111