Acetyltransferase required for the establishment of sister chromatid cohesion. Couples the processes of cohesion and DNA replication to ensure that only sister chromatids become paired together. In contrast to the structural cohesins, the deposition and establishment factors are required only during S phase. Acts by mediating the acetylation of cohesin component SMC3. acetyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-acetyl-L-lysyl-[protein] The subunit structure is controversial. Monomer. Homodimer. Nuclear at interphase, associated with chromosomes during mitosis. The N-terminal region seems to be responsible for association with chromosomes, thus excluding any involvement of the Zn finger in this process. Phosphorylated during mitosis. Belongs to the acetyltransferase family. ECO subfamily.