Anti-CD46 molecule antibodies are used in the immunodetection of the protein encoded by the CD46 gene. In humans, the canonical protein has a reported length of 392 amino acid residues and a mass of 43.7 kDa. Its subcellular localization is in the cytoplasmic vesicles. Alternative splicing is reported to yield 16 different isoforms for this protein. It is noted to be expressed by all cells except erythrocytes. It is known to act as a cofactor for complement factor I, a serine protease which protects autologous cells against complement-mediated injury by cleaving C3b and C4b deposited on host tissue. Post-translational modifications have been described, including O-glycosylation, N-glycosylation and phosphorylation. Other names for this target antigen include MCP, MIC10, TLX, TRA2.10, membrane cofactor protein, and AHUS2.