IgM in bone marrow-derived lymphocytes. Changes in synthesis, turnover and secretion, and in numbers of molecules on the surface of B cells after mitogenic stimulation

摘要: Stimulation of small, resting B cells by the mitogen lipopolysaccharide from E. coli induces changes in synthesis, turnover, carbohydrate composition, surface deposition and active secretion IgM. With increasing time stimulation, rate synthesis glycoprotein IgM increases over rates syntheses other proteins carbohydrate-containing macromolecules. being actinomycin D-sensitive lymphocytes, becomes more D-resistant. molecules with a median disappearance around 4 h are synthesized amounts. These rapidly turning no longer shed as 7–8 S subunits, but actively secreted 19 pentamers. In form, they contain branch sugars galactose fucose attached to Hμ-chains. Within 20 min after addition unstimulated cells, surface-bound Ig determinants disappear can be approached outside intact anti-Ig antibodies. “De novo” refurnishes original amount within 12 h. Beyond exposure mitogen, appear on surface. At 40 60 between 35 100 times stimulated cells. The majority these turn 5 membrane appears an intermediate station migration out cell during secretion. IgM before mitogenic stimulation is discussed part overall biogenesis membranes