AMINO-TERMINAL DELETIONS IN THE DECORIN CORE PROTEIN LEADS TO THE BIOSYNTHESIS OF PROTEOGLYCANS WITH SHORTER GLYCOSAMINOGLYCAN CHAINS

Analysis of the N-terminal sequence of decorin purified from connectiv e tissues and comparison with the sequence deduced from the cDNA indic ate that the nascent proteoglycan has a 14 amino acid residue N-termin al propeptide. Mammalian expression vectors encoding wild-type decorin and decorin with deletions in the propeptide were used to transform C OS and CHO cells. Cells transformed with vectors encoding deletion var iants of decorin synthesize proteoglycans with shorter galactosaminogl ycan chains than cells transformed with wildtype decorin. This effect on the polysaccharide chain length may be due to a lower affinity betw een the core protein and the glycosyltransferases synthesizing the lin kage region. Alternatively, the deletions may affect the intracellular transport of decorin, An antiserum prepared against the N-terminal pr opeptide immunoprecipitated decorin secreted by cultured cells, showin g that decorin is exported with the N-terminal region intact.