Proteins which mediate the nuclear entry of goat uterine non activated estrogen receptor (naER) following naER internalization from the plasma membrane.

The nuclear transport of the internalised naER is influenced by a 58 kDa protein, p58, that appears to recognize the nuclear localization signals on the naER. At the nuclear pore complex the naER-p58 complex binds to a 62 kDa protein, p62; p58 recognizes p62 in this interaction. It is further observed that p62 gets 'docked' at a 66 kDa nuclear pore complex protein, npcp66. The nuclear entry of naER is an ATP-dependent process. An ATP-dependent biphasic nuclear entry of naER, has been observed. It is possible that the docking of p58-naER complex at the nuclear pore complex and the eventual nuclear entry of naER following its dissociation from the p58 are influenced by two different ranges in the concentration of ATP. In this process, it appears that, the nuclear entry requires an additional quantum of energy, provided by the hydrolysed ATP, in contrast to the energy requirement associated with, the nuclear 'docking' event.