Characterization of plasma membranes and rough endoplasmic reticulum of synovial cells cultured from rheumatoid arthritis patients.

[35S]methionine-labelled plasma membrane (PM) and rough endoplasmic reticulum (RER) proteins were analysed from synovial cell cultures derived from rheumatoid arthritis (RA) and reference patients. Pure RER was prepared by a modification of CsCl-containing sucrose-cushion method. The PM proteins were resolved into 30-35 bands using sodium dodecyl sulphate-electrophoresis in polyacrylamide gradient gels. The major polypeptides had apparent molecular masses of 170, 140, 110, 60, 40, 33, 23 and 14 kilodaltons. The major RER polypeptides had the apparent molecular masses of 170, 74, 58 and 35 kD. No reproducible differences were demonstrated in the polypeptide patterns or in the specific activities of the PM and ER (endoplasmic reticulum) marker enzymes between cells from RA and reference patients. The results reflect similarities of membrane structures in RA and reference cells, although differences have been reported in their metabolism.