Which type of lipid acts as signaling molecules in the body?

Steroids are a type of lipid that acts as signaling molecules in the body due to their unique structure and ability to pass through cell membranes easily. They are characterized by a four-ring carbon structure, which allows them to interact with specific receptors inside target cells. Once inside a cell, steroids can influence gene expression by binding to nuclear receptors, leading to the production of proteins that regulate a wide range of biological processes, including growth, metabolism, and immune response.

This signaling capacity is significant because steroids include hormones such as testosterone, estrogen, and cortisol, which play vital roles in various physiological functions. Their ability to function as signaling molecules distinguishes them from other lipid types, which serve different purposes; for instance, fats primarily serve as energy storage and insulation, phospholipids are key components of cell membranes, and waxes are typically found in protective coatings. Thus, the role of steroids in cellular signaling underscores their importance in maintaining homeostasis and responding to physiological changes.