olog ous ▁recom bin ation ▁and ▁DNA ▁looping . ▁C oh es in ▁is ▁formed ▁of ▁S MC 3 , ▁S MC 1 , ▁R AD 2 1 ▁and ▁S CC 3 ▁( SA 1 ▁or ▁SA 2 ▁in ▁humans ). ▁C oh es in ▁holds ▁sister ▁chrom at ids ▁together ▁after ▁DNA ▁rep lication ▁until ▁an aph ase ▁when ▁removal ▁of ▁coh es in ▁leads ▁to ▁separation ▁of ▁sister ▁chrom at ids . ▁The ▁complex ▁forms ▁a ▁ring - like ▁structure ▁and ▁it ▁is ▁believed ▁that ▁sister ▁chrom at ids ▁are ▁held ▁together ▁by ▁ent rap ment ▁inside ▁the ▁coh es in ▁ring . ▁C oh es in ▁is ▁a ▁member ▁of ▁the ▁S MC ▁family ▁of ▁protein ▁complex es ▁which ▁includes ▁Cond ens in , ▁M uk BE F ▁and ▁S MC - Sc p AB . ▁ ▁C oh es in ▁was ▁separately ▁discovered ▁in ▁bud ding ▁ye ast ▁by ▁Douglas ▁K osh land ▁and ▁Kim ▁Nas my th . ▁ ▁Str ucture ▁ ▁C oh es in ▁is ▁a ▁multi - sub unit ▁protein ▁complex , ▁made ▁up ▁of ▁S MC 1 , ▁S MC 3 , ▁R AD 2 1 ▁and ▁S CC 3 ▁( SA 1 ▁or ▁SA 2 ). ▁S MC 1 ▁and ▁S MC 3 ▁are ▁members ▁of ▁the ▁Struct ural ▁Main ten ance ▁of ▁Ch rom os om es ▁( S MC ) ▁family . ▁S MC ▁prote ins ▁have ▁two ▁main ▁struct ural ▁characteristics : ▁an ▁ATP - binding ▁c ass ette -