SMC1B

Description

The SMC1B (structural maintenance of chromosomes 1B) is a protein-coding gene located on chromosome 22.

SMC1B (Structural Maintenance of Chromosomes protein 1B) is a protein involved in chromosome organization and is crucial for meiosis. It belongs to a family of proteins responsible for sister chromatid cohesion and DNA recombination during cell division. SMC1B works alongside other cohesin proteins like REC8, STAG3, and SMC3 to maintain cohesion between sister chromatids throughout meiosis in human oocytes. SMC1B has three key roles in meiosis. It participates in chromosome fusion during meiosis, both for homologous and non-homologous chromosomes. It also helps form axial elements (AEs), which are structures found in synaptonemal complexes, along with other cohesin proteins like REC8 and SMC3, and AE proteins SCP2 and SCP3. Lastly, SMC1B provides sister chromatid cohesion in meiosis. Interestingly, SMC1B can protect telomeres from damage, a function not observed in its related protein SMC1A. In somatic cells, SMC1B forms a mitotic cohesin complex with SMC3 and RAD21, a complex previously thought to only contain SMC1α. Depletion of SMC1B in somatic cells has been linked to dysregulation of gene expression.

SMC1B is a critical component of the cohesin complex, specifically involved in meiosis. While not essential for the initial establishment of sister chromatid cohesion, it is crucial for its maintenance throughout meiosis. This protein contributes to the formation of axial elements (AEs) within synaptonemal complexes, facilitating the organization of chromatin loops along these structures. SMC1B plays a key role in synapsis, the pairing of homologous chromosomes, and in the recombination and movement of chromosomes during meiosis. The cohesin complex, which SMC1B is part of, forms a ring-like structure that holds sister chromatids together after DNA replication. This complex remains attached to the chromatids until anaphase, when it is cleaved and dissociates, allowing the separation of the sister chromatids. During prophase I of meiosis, the meiosis-specific cohesin complex, including SMC1B, is thought to replace the mitosis-specific complex.

SMC1B is also known as SMC1BETA, SMC1L2.

Associated Diseases

• myoepithelial tumor
• male infertility with teratozoospermia due to single gene mutation
• partial chromosome Y deletion
• spermatogenic failure 61
• spermatogenic failure 73
• spermatogenic failure 74
• spermatogenic failure 48
• spermatogenic failures 50
• spermatogenic failure 25