Both the antiserum and IgG fractions of anti-Carboxypeptidase Y (Baker's Yeast) are shown to detect under reducing conditions of SDS-PAGE the 61,000 dalton enzyme in cellular extracts. Approximately 10 μg of total protein is loaded per lane. A 1:5,000 dilution of the primary antibody is used followed by detection using HRP Goat-anti-Rabbit IgG (H&L) diluted 1:4,000 and color development using 4-CN substrate until sufficient color develops. Other detection systems will yield similar results.