HREs can differ from each other in three significant ways. Four paradigms for how hormone response elements can be configured have been determined as shown. Classical methods in biochemistry to characterize receptors are still important. The purified receptors can be recovered from the column by elution with aldosterone solution. There are typically 1000 - 10,000 steroid receptors per cell.
Steroids usually have no net charge or charged functional groups.
The flip side of this is that similary weak forces hold steroid molecules when held together in crystals. One may expect that the conformation of steroid hormones obtained from X-ray crystal structures should approximate the hormone conformations adopted when binding to its receptor. The mRNA transcribed may be for an enzyme which permits the production of another protein or a chemical messenger. This other protein or messenger may control the responses of which the particular cell is capable. Thus, the net effect may be a combination of transcriptional upregulation for proteins enhancing a particular cellular response while contradictory or unnecessary protein synthesis would be inhibited.