Inositolfosfolipidien

Inositolfosfolipidit, often referred to as phosphoinositides, are a class of lipids found in cell membranes. They are derived from inositol, a cyclic sugar alcohol, and a phosphate group, attached to the glycerol backbone of a phospholipid. Their primary role is in cell signaling and regulating various cellular processes. These molecules are not static components of the membrane but are dynamically phosphorylated and dephosphorylated by specific enzymes, creating a diverse array of signaling molecules.

The most well-studied inositolfosfolipid is phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 serves as a precursor for important second messengers, notably inositol trisphosphate (IP3) and diacylglycerol (DAG), which are released upon stimulation of certain cell surface receptors. IP3 mobilizes calcium ions from intracellular stores, while DAG activates protein kinase C. Different phosphorylation patterns of the inositol ring create a variety of phosphoinositide species, each with distinct roles in cellular functions such as membrane trafficking, cytoskeletal organization, and cell growth. The precise composition and localization of these lipids within the cell are crucial for maintaining cellular homeostasis and responding to external stimuli.