Acoustic NMR in spin-1 systems

Abstract

The cell surface of G8-1 clonal muscle cells was labelled at different stages of myogenesis by a variety of methods. Lactoperoxidase-catalysed iodination revealed five surface proteins of 205K (daltons), 160K, 70K, 64K, and 53K which were expressed on myoblast cells only. Four components of 150K, 140K, 54K, and 36K were expressed in myotube cultures only. Labelling of cell-surface sialoglycoproteins by periodate-tritiated borohydride detected the same four myotube-specific components of 150K, 140K, 54K, and 36K that were labelled by lactoperoxidase iodination. Cellular glycoprotein expression during myogenesis was detected by staining polyacrylamide gels of separated muscle components with 125I-concanavalin A (Con A) or 125I-wheat germ agglutinin (WGA). 125I-Con A identified seven glycoproteins of molecular weights, 89K, 76K, 74K, 61K, 52K, 35K, and 27K, which were synthesised in myoblasts and in myotubes at an early stage of differentiation and whose synthesis was then switched off. 125I-WGA detected a myoblast-specific glycoprotein of 100K and a glycoprotein of 89K which was not synthesised in mature myotubes. Fibronectin was labelled by each of the four probes and a similar pattern of regulation was found with each. Fibronectin is synthesised in low amounts in myoblasts. Its level increases with cell fusion and myotube formation to a maximum at the first myotube time point. Its level then falls as the myotubes differentiate. A similar mode of regulation was found with the major Con A receptor (48K) and the major WGA receptor (82–87K).