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Hormone Transport Binding Proteins

Meaning

Specialized protein molecules, primarily synthesized in the liver, that circulate in the bloodstream and reversibly bind to lipophilic hormones, such as sex steroids (testosterone, estradiol) and thyroid hormones. These proteins, including Sex Hormone Binding Globulin (SHBG) and Thyroxine-Binding Globulin (TBG), serve to transport hormones throughout the body and act as a circulating reservoir, protecting them from rapid metabolic clearance. The concentration of these binding proteins directly influences the fraction of “free” or biologically active hormone available to target tissues.