Answer:
1) The action of a protein hormone is faster as compared to steroid hormone.
2) Protein hormone requires cell surface receptors in order to cause signal transduction while steroid hormone does not require such receptors on cell membrane because it can directly cross the cell membrane.
Explanation:
1) Reason behind faster response of protein hormone as compared to steroid hormone: Protein hormones after interaction with their receptors use intermediates already lying within the cytosol and do not need synthesize the intermediates via nuclear expression. So a few steps are skipped during signal transduction/cellular signalling. In contrast to this, a steroid hormone after crossing the cell membrane reaches the cytosol where it interacts with the steroid hormone receptors (SHRs). After this interaction, it is bound to cause synthesis of intermediates via nuclear expression which can only occur if it enters the nucleus. When these intermediates get synthesized with the help of hormone response elements lying within DNA then only signal transduction can proceed further. So, the mechanism of action of steroid hormones requires more steps than protein hormones leading to slower response as compared to protein hormones.
2) Difference in receptors: The receptors meant for protein hormones are cell surface receptors which are present within the cell membrane. For example: G-protein coupled receptors/ RTK receptors. The receptors meant for steroid hormones are cytosolic/cytoplasmic, steroids do not require receptors on the surface of cell membrane because they can directly cross cell membrane because their composition is same as of cell membrane ( both have hydrophobic nature/ both are made up of lipids). For example: Glucocorticoid receptor, estrogen receptor etc..
Answer:
The major differences in the mechanism is due to their hydrophobic (steroid hormone) and hydrophilic nature (protein).
Explanation:
Steroid hormones are the hydrophobic molecules that are easily cross the cell membrane of the targeted cell and complete their action. The actions that are initiated by the steroid hormones are slower but sustained.
Protein hormones in other hand are hydrophilic molecules that do not cross the cell membrane and bind to the receptors present on the surface of the cell and initiate its action. These actions are dramatic and brief.
Thus, the correct answer is - The major differences in the mechanism is due to their hydrophobic (steroid hormone) and hydrophilic nature (protein).
