Abstract
The lipocalin protein family is a large group of small extracellular proteins. The family demonstrates great diversity at sequence level; however, lipocalin crystal structures are highly conserved and comprise a single eight-stranded antiparallel β-barrel, which encloses an internal ligand-binding site.
They have been associated with a variety of different functions, among them transport of retinoids, steroids, bilins, pheromones, enzymic synthesis of prostaglandins, cryptic coloration, olfaction, immune response, cell regulation. Lipocalin-2 (also known as neutrophil gelatinase-associated lipocalin), which is a useful biomarker for early detection of various renal injuries, shows pleiotropic bioactivities in a variety of different cell types and tissues.
It plays important roles in angiogenesis, apoptosis, organogenesis, inflammation, hematopoiesis, wound healing, renal physiology, tumor and reproductive biology.