FRACTIONATION AND IDENTIFICATION OF PIG LYMPH-NODE PLASMA-MEMBRANE GLYCOPROTEINS

Plasma membrane vesicles purified from pig mesenteric lymph node tissue were solubilized in 1% (wt/vol) sodium deoxycholate and the fractionation of both membrane proteins and glycoproteins was assessed by gel filtration on AcA 34. Milligram quantities of the glycoprotein fraction, consisting of 12 distinct bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis ranging in apparent MW from 12,000 to 250,000, were purified by affinity chromatography on lentil lectin-Sepharose. Identified among these by specific immunoprecipitation were the major histocompatibility antigen, SLA (band 9), in association with .beta.2-microglobulin (band 12), and the .alpha. (band 10) and .beta. (band 11) subunits of the Ia-like antigens. A tentative identification of membrane-bound IgM, IgG and IgA was also proposed on the basis of their known affinities for protein A. Thus, the domestic pig represents an inexpensive, abundant source of defined lymphocyte plasma membrane glycoproteins suitable for further structural analysis.