Final answer:
Albumin is the most abundant plasma protein, accounting for about 54 percent of total plasma proteins, essential for transport and maintaining osmotic pressure.
Step-by-step explanation:
The protein that makes up more than half of plasma proteins is albumin. Albumin is predominantly manufactured by the liver, and it plays a vital role in the body. Not only does it function as a binding protein that serves as a transport vehicle for substances like fatty acids and steroid hormones, but it also contributes significantly to the osmotic pressure of blood. This is vital for maintaining blood volume and blood pressure by retaining water within the blood vessels and drawing it from the tissues into the bloodstream. Albumin constitutes approximately 54 percent of the total plasma protein content, with clinical levels ranging between 3.5-5.0 g/dL of blood.