Structural maintenance of chromosome proteins (SMC) are involved in chromosome cohesion during cell cycle and in DNA repair as part of the of cohesin complex. The cohesin complex is 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. Involved in DNA repair via its interaction with BRCA1 and its related phosphorylation by ATM, or via its phosphorylation by ATR. Works as a downstream effector both in the ATM/NBS1 branch and in the ATR/MSH2 branch of S-phase checkpoint The form of SMC1A phosphorylated at Ser-957 and Ser-966 associates with chromatin during G1/S/G2 phases but not during M phase, suggesting that phosphorylation does not regulate cohesin function.Synonyms: DXS423E, SB1.8, SMC protein 1A, SMC-1-alpha, SMC-1A, SMC1L1, Structural maintenance of chromosomes protein 1A