Fluorescent conjugates of ovalbumin and bovine serum albumin. The COUP acronym stands for chicken ovalbumin upstream promoter. The most common carriers include serum globulin, albumins, ovalbumin and many others. Ovotransferrin makes up approximately 13% of egg albumen (in contrast to ovalbumin, which comprises 54%). Ovalbumin in solution is heat-resistant. The non-inhibitory serpin ovalbumin is the most abundant protein in egg white. Two amino acid storage proteins in animals are casein and ovalbumin. Also, ovalbumin is frequently contaminated with endotoxins. Ovalbumin is the most abundant protein in albumen. The function of ovalbumin is unknown, although it is presumed to be a storage protein.