What is the Origin of Polypeptide Hormones?

The classification of hormones into different chemical classes, including peptides, steroids, and amines, emerged from early 20th-century biochemistry and endocrinology as scientists began to isolate and characterize these regulatory substances. The term "polypeptide" is a chemical descriptor, indicating a polymer chain of amino acids, and is a foundational concept in molecular endocrinology.

What is the Mechanism of Polypeptide Hormones?

The mechanism of action for polypeptide hormones is initiated by binding to a transmembrane receptor, which then triggers a cascade of intracellular events known as a second messenger system. This signaling cascade often involves the activation of enzymes, phosphorylation of proteins, or changes in gene expression within the cell. Because the signal is amplified inside the cell, even small amounts of these potent hormones can elicit significant and widespread physiological responses.

Polypeptide Hormones ∞ Area

Polypeptide Hormones

Meaning

Polypeptide hormones are a class of signaling molecules synthesized from chains of amino acids, ranging from short peptides to larger, more complex proteins, which regulate diverse physiological functions throughout the body. Unlike steroid hormones, these molecules are typically water-soluble, cannot cross the cell membrane, and exert their effects by binding to specific receptors on the surface of target cells. Key examples include insulin, growth hormone, and Gonadotropin-Releasing Hormone (GnRH), all vital for metabolic and endocrine health.