Mannose 6-Phosphate Receptor Proteins from Reptiles and Amphibians: Evidence for the Presence of MPR 300 and MPR 46

Two mannose 6-phosphate receptors (MPR 300 and MPR 46) are involved in transport of lysosomal enzymes. Both receptors are expressed in all mammalian species studied so far and in chicken. Here we present the first report on affinity purification of both MPRs from the liver tissues of reptiles and amphibians using Sepharose divinyl sulfone phosphomannan at pH 7.0. MPR 300 from both species show similar electrophoretic mobility as mammalian MPR 300 and cross-react with an antibody directed against MPR 300 from goat liver. Furthermore, MPR 46 from reptilian liver and amphibian oocytes cross-react with peptide-specific antibodies against the cytoplasmic domain of human MPR 46 (anti-MSC1).