What is the Origin of Hormone Transport Globulins?

This concept is fundamental to classical endocrinology, established through the study of protein-hormone interactions and their role in endocrine homeostasis. The recognition of these proteins clarified why total hormone levels do not always correlate directly with clinical effect. The term reflects the physiological necessity of solubilizing lipophilic hormones for systemic transport and providing a circulating reservoir.

What is the Mechanism of Hormone Transport Globulins?

Hormone transport globulins function as modulators of hormonal bioavailability; only the unbound, or "free," fraction of the hormone can diffuse across cell membranes to interact with intracellular receptors. Changes in the concentration or binding affinity of these globulins, often influenced by liver function or insulin status, can significantly alter the effective hormonal signal delivered to target tissues. They serve as a crucial buffer system within the endocrine network.

Hormone Transport Globulins

Meaning

A class of plasma proteins, primarily synthesized in the liver, that reversibly bind and transport steroid and thyroid hormones throughout the circulatory system. Key examples include Sex Hormone-Binding Globulin (SHBG) and Thyroxine-Binding Globulin (TBG). These globulins regulate the fraction of hormones that are biologically active, thereby controlling tissue exposure and overall endocrine signaling.