Evidence against lung galaptin being important to the synthesis or organization of the elastic fibril

Abstract

Previously it has been suggested that galaptin, an endogenous beta-galactoside-binding lectin, may function in the organization of lung elastic fibres. Galaptin was not present in preparations of rat or porcine lung elastic fibrils, neither did it bind to any of the fibril-associated proteins when these were separated by SDS/polyacrylamide-gel electrophoresis. Elastin and galaptin synthesis and secretion were investigated in lung fibroblast cultures and in anatomically preserved slices from developing rat lung. In both systems the synthesis and secretion of elastin was unmodified by the presence of beta-galactosides or antigalaptin in the culture medium. The synthesis of galaptin was unmodified by the presence of anti-elastin or beta-aminoproprionitrile in the culture medium. Cultured fibroblasts secreted elastin but only trivial amounts of galaptin. When cultures were treated with iodoacetamide (10(-5)M) galaptin synthesis was maintained but elastin synthesis ceased. These results argue against galaptin having an important role in the synthesis, secretion or organization of the elastic fibril.