Molecular aspects and natural source of procalcitonin

The search for sensitive and specific markers of systemic infection has sho wn that procalcitonin levels are increased in sepsis, and, consequently, th is plasma protein has come into the focus of clinical research. Human proca lcitonin is encoded by the Calc-I gene, which gives rise to two alternative ly spliced transcripts. Despite systemic investigation of the Calc-I gene a nd mechanisms of the tissue-specific regulation and alternative splicing, l ittle is known about the biology of procalcitonin and the cells which expre ss this protein during inflammation. Here we focus on the molecular and bio chemical properties of the molecule and summarize the known biological func tions of procalcitonin. We report on the structure of the Calc-I gene, the amino acid conservation of procalcitonin in different species, and the cons ensus sequences of the protein with regard to sites relevant for posttransl ational modification, spatial distribution, and homologies to other cytokin es. We discuss aspects of intracellular location of procalcitonin and demon strate that it has the characteristics of a secreted protein.