Abstract
Chicken muscle cells secrete characteristic proteins when grown in the serum-free and hormonally defined culture medium ‘DMN’. The most prominent band detected by gel electrophoresis represents a protein of mol.wt 22,000. Fibroblasts released a mol.wt 16,000 protein and fibronectin (mol.wt 220,000) into the medium. The mol.wt 22,000 protein band resolved in 2 dimensional gels into 2 spots which migrated to the same positions as small heat shock proteins as well as butyrate-inducible proteins (BIP) which can be demonstrated in whole cell extracts after butyrate treatment in the presence of serum. The synthesis and release of the mol.wt 22,000 protein is repressed by supplementing the culture medium with serum but not with chick embryo extract.