Inter molecular and intra molecular di sulfide bonding among lymphocyte plasma membrane proteins and glyco proteins
Allore, R.J.; Barber, B.H.
Molecular Immunology 20(4): 383-396
ISSN/ISBN: 0161-5890 Accession: 005719335
The disulfide bonding characteristics of the pig lymph node plasma membrane (PM) proteins and glycoproteins were examined by 1- and 2-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Reaction of the purified PM vesicles with N-ethyl maleimide (NEM) prior to detergent solubilization markedly reduced the extent of intermolecular disulfide bonding subsequently observed. The blocking of free SH groups with NEM prevented the detergent-induced disulfide bonding of numerous components, including PM-bound actin. The extent of intermolecular disulfide bonding among the NEM-pretreated PM glycoproteins purified by lentil lectin affinity chromatography was relatively limited, with only 3% of the total glycoprotein present as intermolecular disulfide-bonded complexes. The degree of intramolecular disulfide bonding revealed by a modified 1-dimensional SDS-PAGE technique was quite striking. Among those polypeptides demonstrating a clearly altered mobility upon reduction was the H chain of class I and .beta.-chain of class II major histocompatibility complex (MHC) antigens. The class II .alpha.-chain was much less affected. The changes were compared with those observed for proteins containing intramolecular disulfide-bonded domains of known size and number, and considered in the light of recent information on the structure of MHC antigens.