Final answer:
Estrogen affects transport proteins by binding to them, increasing solubility in blood, and preventing hormonal degradation. It also plays a role in gene expression, lipid metabolism, and oxygen delivery. Antagonistic molecules could block estrogen's effects by preventing receptor binding.
Step-by-step explanation:
Estrogen has a significant effect on transport proteins like Thyroxine Binding Globulin (TBG) and Sex Hormone Binding Globulin (SHBG). These proteins are crucial for the transport of hydrophobic hormones in the bloodstream, as they allow insoluble molecules like estrogen, a steroid hormone, to become soluble in blood. Estrogen is a 19 carbon compound synthesized from cholesterol, with pregnenolone as an intermediate. It is controlled by Gonadotropin hormones (GnRH) including Follicle Stimulating Hormone (FSH), and it circulates in blood bound to SHBG. By binding to transport proteins, estrogen is protected from degradation by circulating enzymes, ensuring that signals mediated by estrogen can be effective over longer durations within the body. Furthermore, estrogen influences gene expression by crossing plasma membranes and binding to receptors inside target cells. It also plays a role in lipid metabolism by affecting the levels of high-density lipoprotein (HDL) and low-density lipoprotein (LDL), thus contributing to the prevention of atherosclerosis.
In addition, certain hormones like estrogen can impact oxygen delivery in the body by stimulating the production of 2,3-bisphosphoglycerate (BPG), which promotes the disassociation of oxygen from hemoglobin. This ability of estrogen to interact with various proteins and systems underlines the hormone's versatility and the critical role it plays in biological processes. Any antagonist molecule that binds to plasma membrane receptors would block the action of steroid hormones like estrogen and testosterone, preventing them from exerting their physiological effects.