Bovine serum albumin (BSA). Computer illustration showing the structure of a molecule of bovine serum albumin. Serum albumin is produced by the liver. It is found dissolved in blood plasma and is the most abundant blood protein in mammals. One of it's functions is to transport fatty acids to the liver. It also binds to molecules, including calcium, some hormones and drugs, to prevent them from being filtered from the blood by the kidneys. Albumin is also important in regulating plasma volume.