Possible role as a cell-adhesion or receptor molecule of erythroid cells. Expressed in erythroid-enriched bone marrow (at protein level). Highly expressed in bone marrow and to a lower extent in leukocytes, thymus, lymph node and spleen. Expressed in fetal liver blood cells (at protein level). Highly expressed in fetal liver. Glycosylated. ERMAP is responsible for the Scianna/Radin blood group system which comprises seven different antigens (PubMed:12393480). The Sc1 and Sc2 antigens are resulting from a single variation in position 57; Arg-57 corresponds to the Sc2 antigen and Gly-57 to the Sc1 antigen. The Sc2 antigen is rare with an occurrence of less than 1% in the population while Sc1 is more frequent. Sc3 is not expressed by individuals homozygous for a null allele encoding a truncated protein lacking its extracellular part (Sc-3). The Sc4 antigen corresponding to the previously defined Radin blood group antigen (Rd) is due to a single variation in position 60; Ala-60 corresponds to Sc4/Rd(+), the antigenic form of the protein. Sc4 is found in less than 1% of the population. Sc5/STAR, Sc6/SCER and Sc7/SCAN antigens are due to single variations in positions 47, 81 and 35 respectively. Alloantibodies to the low frequency Sc2 and Sc4 antigens are the cause of hemolytic disease in the newborn (PubMed:15660834, PubMed:16371048). Belongs to the immunoglobulin superfamily. BTN/MOG family. Blood group antigen gene mutation database