Plasma proteins, also termed
serum proteins or
blood proteins, are
proteins present in
blood plasma. They serve many different functions, including transport of lipids, hormones, vitamins and minerals in the circulatory system and the regulation of
acellular activity and functioning of the
immune system. Other blood proteins act as enzymes, complement components,
protease inhibitors or
kinin precursors. Contrary to popular belief,
hemoglobin is not a blood protein, as it is carried within
red blood cells, rather than in the blood serum.