Microglobulin protein. Molecular models of two overlapping views of the protein beta-2 microglobulin. This protein, with a relatively small molecular mass, is part of the immunoglobulin protein family. It is a monomeric peptide chain of 99 amino acids. It has seven beta-strands (arrowed ribbons). It is a cell surface protein, found on nearly all cells in the body. It can aggregate into fibres to form amyloid deposits, especially in patients on long-term dialysis. The two models shown here are a tubular one (background; 913 atoms) and the protein shape (foreground; sheets, ribbons and arrows).