Lymphocyte Antigen 86 (LY86)

The deduced MD1 protein contains 162 amino acids, shares 66% amino acid identity with mouse Md1, and has a predicted 19-amino acid signal peptide and 2 N-glycosylation sites. Six of 7 cysteine residues in human MD1 are conserved in mouse and chicken Md1.

Northern blot analysis detected a 1.0-kb MD1 transcript in B-cell lines and the U937 monocyte line, but no expression was detected in 2 T-cell lines or in the K562 erythroleukemia line. Western blot and flow cytometry analysis demonstrated that expression of MD1, an approximately 25-kD protein, enhances surface expression of RP105. The authors found that MD1 is also expressed on the surface despite its lack of a transmembrane region.