Mast Cell Expressed Membrane Protein 1 (MCEMP1)

The deduced 186-amino acid protein contains a single transmembrane domain and has a calculated molecular mass of 21.2 kD. MCEMP1 expression was detected in cell lines derived from mast cell leukemia and acute monocytic leukemia tissues and in CD14-positive monocytes, but not in other lymphocytes or epithelial cells. RT-PCR detected MCEMP1 in lung and at lower levels in other tissues containing mast cells. In cultured primary mast cells, maximal expression was reached at 5 weeks in culture. MCEMP1 localized to the membrane fraction of transfected human embryonic kidney cells. Immunostaining of differentially permeabilized cells showed that the C terminus was exposed to the outside of the cell membrane and the N terminus was cytoplasmic. Western blot analysis detected MEMP1 at an apparent molecular mass of 22 kD.