Final answer:
The protein/receptor complex at the nuclear site is disrupted by mechanisms including ATP hydrolysis for active transport into the nucleus, allosteric changes upon hormone binding, and targeted protein degradation involving ubiquitins and proteasomes.
Step-by-step explanation:
At the nuclear site, the disruption of the protein/receptor complex takes place through several mechanisms. One primary mechanism involves the hydrolysis of ATP, which provides the energy required for protein conformational changes and active transport of nuclear proteins into the nucleus. This process is facilitated by nuclear localization signals and nuclear transport receptors.
Upon hormone binding, a nuclear receptor (NR) which is initially in the cytoplasm and bound to a heat shock protein (HSP), dissociates from the HSP and undergoes an allosteric change. This change permits the hormone-bound receptor to pass through the nuclear pore. Once inside the nucleus, the hormone-receptor complex binds to a hormone response element (HRE) triggering gene transcription and translation, ultimately altering cell function.
The target protein, if marked for degradation, can be unfolded through ATP hydrolysis, where ubiquitins are released, and then the target protein enters the proteasome, a structure responsible for breaking down proteins.