An ELISA method to quantify the mannose 6-phosphate receptors

Mannose 6-phosphate receptor proteins mediate transport of lysosomal enzymes to lysosomes in eukaryotes. Two receptors designated as MPR 300 and MPR 46 based on their apparent molecular mass have been well studied from human and bovine liver. In humans, it has been shown that the receptors are present in different concentrations in different tissues. In the present study, MPR 300 and MPR 46 were purified from goat liver by phosphomannan affinity chromatography, and polyclonal antibodies were raised in rabbits. MPR 300 receptor specific antibodies have been purified from the antiserum using a goat-MPR 300-receptor gel. Using this affinity-purified antibody and the antiserum to goat MPR 46, as well as an affinity-purified MSC1 antibody that is specific for MPR 46, we developed an ELISA method to quantify both the receptors. The receptors could be measured in the concentration range of 1-10 ng using ELISA. The receptors could be quantified from membrane extracts of different tissues of goat and chicken using this method.