LEM Domain Containing Protein 3 (LEMD3)

The MAN antigens, such as MAN1, are nuclear membrane proteins that are recognized by autoantibodies from a patient with a collagen vascular disease. Because MAN1 contains an LEM domain, the gene is also called LEMD3 (for 'LEM domain-containing-3').The deduced 754-amino acid protein has a calculated molecular mass of about 82 kD. MAN1 contains an N-terminal LEM domain, followed by 2 globular segments, the second of which contains 2 transmembrane regions. Northern blot analysis detected a 5.5-kb transcript expressed at variable levels in all tissues and cell lines examined, with highest level in placenta and lowest level in a lung carcinoma cell line. Western blot analysis revealed 2 endogenous MAN1 proteins with apparent molecular masses of 82 and 60 kD in HeLa cell lysates.