As a member of the cohesin complex, involved in sister chromatid cohesion from the time of DNA replication in S phase to their segregation in mitosis, a function that is essential for proper chromosome segregation, post-replicative DNA repair, and the prevention of inappropriate recombination between repetitive regions (PubMed:11509732). The cohesin complex may also play a role in spindle pole assembly during mitosis (PubMed:11590136). In interphase, cohesins may function in the control of gene expression by binding to numerous sites within the genome (By similarity).

May control RUNX1 gene expression (Probable). Binds to and represses APOB gene promoter (PubMed:25575569). May play a role in embryonic gut development, possibly through the regulation of enteric neuron development (By similarity)

Component of the cohesin complex, which consists of an SMC1A/B and SMC3 heterodimer core and 2 non-Smc subunits RAD21 and STAG1/SA1, STAG2/SA2 or STAG3/SA3 (PubMed:10931856, PubMed:11590136, PubMed:22628566, PubMed:25575569, PubMed:32409525). Interacts (via C-terminus) with SMC1A and (via N-terminus) with SMC3; these interactions are direct (PubMed:12198550, PubMed:32409525). The cohesin complex interacts with NUMA1 (PubMed:11590136).

The cohesin complex also interacts with CDCA5, PDS5A and PDS5B; this interaction might regulate the ability of the cohesin complex to mediate sister chromatid cohesion (PubMed:15837422). The interaction with PDS5B is direct and is stimulated by STAG1/SA1 (PubMed:19696148). The cohesin complex interacts with the cohesin loading complex subunits NIPBL/Scc2 (via HEAT repeats) and MAU2/Scc4 (PubMed:22628566).

NIPBL directly contacts all members of the complex, RAD21, SMC1A/B, SMC3 and STAG1 (PubMed:32409525). The cohesin complex interacts with DDX11/ChIR1 (PubMed:17105772). Directly interacts with WAPL; this interaction is stimulated by STAG1/SA1 (PubMed:19696148).

Interacts with the ISWI chromatin remodeling complex component SMARCA5/SNF2h; the interaction is direct (PubMed:12198550). Interacts with the NuRD complex component CHD4; the interaction is direct (PubMed:12198550)

Expressed in the gut (at protein level)

The C-terminal part associates with the ATPase head of SMC1A, while the N-terminal part binds to the ATPase head of SMC3

• Cornelia de Lange syndrome 4 with or without midline brain defects (CDLS4)

  A form of Cornelia de Lange syndrome, a clinically heterogeneous developmental disorder associated with malformations affecting multiple systems. It is characterized by facial dysmorphisms, abnormal hands and feet, growth delay, cognitive retardation, hirsutism, gastroesophageal dysfunction and cardiac, ophthalmologic and genitourinary anomalies.

• Mungan syndrome (MGS)

  An autosomal recessive disease characterized by visceral neuromyopathy, intestinal dysmotility and chronic intestinal pseudoobstruction, megaduodenum, long-segment Barrett esophagus, and a variety of cardiac valve or septal defects such as membranous ventricular septal defect, pulmonary and tricuspid valve regurgitation.