Essential protein required for cell fate determination during embryogenesis. Involved in sister chromatid cohesion. Forms a complex with SCC2, which is required for the association of the cohesin complex with chromosomes. Interacts with SCC2 to form the cohesin loading complex. Associates with chromatin, especially during telophase, prophase and interphase. Mostly localized in the nucleus during interphase and preprophase stages, but not in the nucleolus. During prometaphase, metaphase, anaphase and telophase, mostly cytoplasmic. Expressed ubiquitously. Defective embryo arrested at preglobular/early globular stage. Suspensor overproliferation phenotype preceded by ectopic auxin maxima distribution. Reduced efficacy of cohesin immobilization in nuclei. Belongs to the SCC4/mau-2 family.