Fc Receptor, IgA, IgM, High Affinity (FCAMR)

The deduced 532-amino acid protein, which is 49% identical to the mouse sequence, has a 10-amino acid leader sequence; a 440-amino acid extracellular region with 2 potential N-linked glycosylation sites and a pair of cysteine residues potentially involved in forming the Ig-like domain; a 20-amino acid transmembrane region; and a 62-amino acid cytoplasmic tail. The human FCAMR cytoplasmic tail lacks a dileucine site implicated in receptor internalization in the mouse protein, suggesting that this function is mediated by a different motif in humans. RT-PCR analysis showed that mouse Fcamr is expressed in multiple tissues, including thymus, liver, spleen, kidney, intestine, testis, and placenta.Functional analysis indicated that mouse Fcamr mediates endocytosis of IgM-coated microbial pathogens.