Serum albumin, the main protein of plasma, has a good binding capacity for water, Ca(2+), Na(+), K(+), fatty acids, hormones, bilirubin and drugs. Its main function is the regulation of the colloidal osmotic pressure of blood (By similarity). Potent inhibitor of trypsin but has no inhibitory effect on thrombin, chymotrypsin, elastase and subtilisin. Plasma. In the skin, widely distributed around the membranes of epithelial layer cells and within the stratum spongiosum of the dermis (at protein level). Belongs to the ALB/AFP/VDB family.