A broad term encompassing numerous proteins, including hemoglobin, albumin, globulins, the acute-phase reactants, transporter molecules, and many others. Normal values are hemoglobin, 13 to 18 g/dl in men and 12 to 16 g/dl in women; albumin, 3.5 to 5.0 g/dl of serum; globulin, 2.3 to 3.5 g/dl of serum. The amount of albumin in relation to the amount of globulin is referred to as the albumin-globulin (A/G) ratio, which is normally 1.5:1 to 2.5:1.