Recent research supports a model where amino terminal domains (NTDs) of steroid hormone receptors (SHR) are predominantly unstructured within a cell but can dynamically respond to the needs of the cell by acquiring a more folded conformation when in proximity to other receptor domains or upon protein-protein interactions. The mineralocorticoid receptor (MR) is a member of the SHR family. Three activation function 1 (AF1) domains have been mapped termed AF1a, MD and AF1b. The current thesis describes a detailed structure function analysis of the MR NTD and its AF1 domains. Data presented suggest that the NTD is in a molten globule like conformation making promiscuous but selective protein-protein interactions. The AF1a and MD regions behave in accordance with an induced folding mechanism showing increased α-helical structure in hydrophobic solvents. No specific interactions were detected for the AF1a region, whereas the MD shows promiscuous protein binding. Specific binding is furthermore shown for the NTD / MD interaction with the general co-activator protein CBP. The experiments also led to the identification of the TATA box protein (TBP) as a MR AF1b specific binding partner. Unlike AF1 domains of other SHRs the MR AF1b is shown to be structured and able to interact specifically with TBP independent of induced folding. Interestingly, circular dichroism spectroscopy revealed that the AF1b polypeptide adopts primarily β secondary structure with little propensity to form α-helix. Data also highlight an important role for hydrophobic amino acid residues within the AF1b region. Results suggest that MR NTD harbours structurally diverse transactivation domains that overall ensure structural plasticity of the MR NTD with yet high specificity in protein-protein interactions.