Structural characterization of the goat uterine estrogen receptor activation factor using an endogenous calcium...

An expedient method for the purification of a calcium activated neutral protease (CANP) of the goat uterus has been designed. This enzyme, purified to homogeneity, has been used as a tool in the structural characterization of the estrogen receptor activation factor II (E-RAF II) that dimerizes with an alternative form of estrogen receptor (ER), the non-activated estrogen receptor (naER). The enzyme cleaves the E-RAF into two fragments, alpha and beta, of molecular mass 32 and 30 kDa, respectively. The beta retains the DNA binding activity, as well as the capacity to dimerize with the naER. On the other hand, the cholesterol binding activity and the ATPase function are shared by both alpha and beta fragments. The E-RAF domain that binds to the nuclear periphery appears to be localized on the beta fragment. The beta fragment, however, is incapable of entering the nucleus on its own.