A lipopeptide is a molecule consisting of a lipid connected to a peptide. Bacteria express these molecules. They are bound by TLR 1, and other Toll-like receptors.
Certain lipopeptides are used as antibiotics. Certain lipopeptides could have strong anifungtal and hemolytic activities. It has been demonstrated that their activity is generally linked to interactions with the plasma membrane  and sterol components of plasma membrane could play a major role and can be their privileged partner of interaction.
^Maget-Dana, R., & Peypoux, F. (1994). Iturins, a special class of pore-forming lipopeptides: biological and physicochemical properties. Toxicology, 87(1-3), 151–74
^Nasir, M. N., Besson, F., & Deleu, M. (2013). Interactions des antibiotiques ituriniques avec la membrane plasmique. Apport des systèmes biomimétiques des membranes. Biotechnology, Agronomy and Society and Environment, 17(3), 505–516.
^Nasir, M. N., & Besson, F. (2012). Interactions of the antifungal mycosubtilin with ergosterol-containing interfacial monolayers. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1818(5), 1302–1308
^Nasir, M. N., & Besson, F. F. (2011). Specific Interactions of Mycosubtilin with Cholesterol-Containing Artificial Membranes. Langmuir : The ACS Journal of Surfaces and Colloids, 27(17), 10785–10792.