Thinnes F P, Hilschmann N, Kayser H, Götz H
Hoppe Seylers Z Physiol Chem. 1983 Dec;364(12):1805-11. doi: 10.1515/bchm2.1983.364.2.1805.
The glycoprotein p31 (also called Ii, In, M1, Dr gamma, XM 1) has been shown up to now only in the membranes of B lymphocytes as well as of epidermal and endothelial cells, where it is always accompanied by antigens of the HLA-DR type. It is therefore called HLA-DR-associated protein. As we show here, the membranes of muscle, liver and brain contain protein molecules with the relative molecular mass Mr = 31 000-33 000 and an isoelectric point around 7.5. These parameters correspond to those of the p31 of B lymphocytes. These molecules, as well as the p31 of B lymphocytes, can be concentrated by ion exchange chromatography. In two-dimensional electropherograms they are identical to those of B lymphocytes. It can therefore be assumed that the po 31 is not really associated with the HLA-DR antigens but is a ubiquitous molecule.
